Thank you for helping this boy! Sounds like you are headed in the right direction with him.
Here are some tricks I've picked up from fostering a feral pack and around 200 basenjis from different backgrounds:
Webmaster harnesses (ruffwear.com) are very secure - a trim basenji with a definite waistline can't pop out of this one.
To get the feral ones used to collars and having collars and harnesses put on them, I introduced them at mealtime. I started out very slow - just draping a rope or leash over their necks when they were eating. They were very food-motivated, though there were a few who I had to start with even more slowly - just leaving a rope or leash next to their food dish while they ate. As they became more comfortable, I would put more on for each meal until they were finally wearing harnesses without a fuss.
To get them used to their nails being done, I used scissor-type clippers with a gentle curve. I let them stand with all four paws on the ground and clipped just the tip of one nail at a time without holding the paw. I would do just one or two at a time with a treat in one hand. They are so easily handled now - I can hold paws without any objection.
Many in the feral pack were too terrified to leave our property, even with other pals along to comfort them. For them, I carried them around for our first 'walks' off of the property, not making a big deal that they were in the safety of my arms - we were just going from point A to point B. After a time or two, they were not trying to hide their heads under my arm. I would then set them down on the ground at the halfway point to have them walk back, not making a big deal if they were mostly crouching.
I've never pressured them with visitors, letting them see I am (and the rest of the pack is) comfortable with visitors or strangers. While I didn't force visitors on them, I also didn't leave access to places like underneath furniture. They did have safe, out of the way spaces where they could go, just not places that left them completely invisible. When walking, I try to make a point of saying hello to people or dogs we see so that the fearful ones will see I'm not afraid of someone approaching. Those fearful of visitors or strangers eventually see by example (mine or the pack) that other humans or dogs aren't bad. Barking dogs were a bit more of a challenge for me to set a good example (I like our non-barkers!), so I tried to compensate by taking in and letting out deep breaths, yawning or talking - "there are those noisy guys who talk too much."
@khaipan A few additional thoughts after yesterday's reply:
I've found that CBD oil is very dose-dependent and may require gradual increases to find an effective amount. I put it in the inside of lips when I give it. Some information I've seen online suggests that it is not as effective if given in treats or on food.
Former fosters have become much more anxious when given the usual sedatives. Benadryl seemed to provide a better response. One of those fosters was extremely anxious because one of her humans was ill. Max could be more anxious if one of his humans is ill - take care of yourselves!
What kind of mental stimulation are you providing? A routine that includes more obedience-type time (more frequent, very short sessions) can help to generally calm Max while building more confidence. Our guys go through a series of commands before every meal. Max may benefit from that communication more frequently.
Sorry to read he is having difficulties alone. I do not recommend the Impact crates, based on the experiences and conditions of one of my former fosters who was returned to me after the crate did not help in that home. He has a leg issue now. I'm not sure if it is a result of panicking in the crate. I have seen dogs damage, even bloody, themselves in crates, including soft plastic. I've also seen teeth damage and damage to some very expensive crates. There is one, a ZenCrate, that is designed to provide relief to those with separation anxiety, though the effect may be realized by leaving music on in the room with the crate. I have no experience with it. I did have one foster who was actually much calmer in his crate and very anxious (and destructive) if left outside of his crate. He was an exception...
Do you currently leave music or tv on? I find they do well when it is just loud enough to cover outside noises - not too loud. Depending on the dog's needs, I find different music or tv shows to be helpful. Happy sitcoms cover the silence with the sounds of people still in the house doing things. 'The Golden Girls' does that while also providing a soothing soundtrack that has put many of our basenjis to sleep. Soft rock has been shown to be soothing in canine studies.
How much in and out practice have you done? By that, I mean going in and out so many times starting with just a very short period of time that your boy won't know if you will be back in two seconds, two minutes, or ten minutes - starting out with just seconds, long enough to lock the door. I don't acknowledge anyone when coming or going when I'm doing this training until we are sitting down, relaxed, on my schedule. First times in and out should be so short that you are back and sitting down before he appears to react. This may mean that you pick up your keys, grab the doorknob, then go sit down. Lots of baby steps.
I prefer to have windows set so that they can watch squirrels, etc., out a back window, yet not see me going and coming out the front window. Blinds can be a safety hazard and face destruction. Our blinds on the front window are on the road side (which cuts down the solar heat load in the house while keeping the blinds out of reach), but you might need to fence off front blinds in your home. Sills may be destroyed.
Two way communication monitoring may help if there is enough noise at your work and during your commute for him to feel like he is still surrounded by life.
I've never not allowed a b to sleep with me unless he had to learn to be less defensive while sleeping first. If I can move them or have them move without being defensive, they are allowed on with everyone else. I don't make a big deal about it. Rather than keeping them out of the bed, I will block them from accompanying me to the bathroom, garage, kitchen, etc.
Since he has been good with just one one companion, adding a new one to the pack may do the trick. You could foster or 'borrow' a friend's dog for a couple of days first to see if this might work before committing to another companion. I do have one basenji who has not been happy when left home alone even if there is another b in the house. He is fine here, though, where there is a pack. One is not enough for him. He needs lots of company..
I hope you find the magic he needs!
@khaipan You are lucky to be able to take Max to work with you. That will allow you to make a home alone transition when you are all ready. He will be sensitive to your feelings, so you need to be ready as much as he is. As long as you don't make a big deal about it, he will be less likely to get excessively attached. My guys are quite attached to me (and, if they are awake, will stay at the window, watching me leave even if my S.O. is here), but they are fine when I'm not here. I've not really acknowledged them when I've left, so they can think that I'm just out on one of many short errands. I can frequently 'sneak out' without them even getting up. Not a big deal.
Before trying daycare again, you might want to approach that at least as slowly as leaving him alone if he's not had the routine of getting together with other dogs. It might also be good to spend the first couple of 'retry' visits with him (hopefully the facility allows for this), letting him have a little fun before leaving. If he's not into other dogs, he will probably be happier home alone. Even if you don't plan on leaving him at daycare regularly, it doesn't hurt to help him learn to like a place just in case you have an emergency need for him to stay.
Whenever we leave, we keep the tv or music going so that they never really feel like we left. They are so used to us coming and going for shorter spells or just going outside to take care of outside chores that they don't get worked up when we go. Of course, we do have quite a few in the house, so they do have company. Even those that have had separation issues in other homes where they have had companions do well here, though, perhaps because we are in and out so frequently. Since you only have a day to come up with a solution, you won't be able to 'practice' the frequent going and coming that we do.
For some, the tv playing sitcom shows may make them feel like family is still 'living around them' even when they are left alone. A quick solution may be doggy daycare until you have more time to do the frequent going and coming practice. You can also set up to have a two-way communication with him instead of just a camera check. I've used Skype and FaceTime to do this. Just hearing our casual talking on FT seems to make a difference for some who didn't stir for hours until the FT audio was muted. There are also remote controlled treat dispensers so they can really think you are magic and always with them even when they can't smell you.
Hope you and Max find a solution that works!
We've had a couple of diabetic basenjis come into rescue. One was around nine years old. Odd case - she never spilled more than a trace of glucose (and is also Fanconi DNA affected), yet her blood glucose when she arrived was 467! She was pretty obese. Not only is she not spilling glucose now, her blood glucose is now normal without insulin and her weight has been healthy for years. We put her on a very rigid diet (Wellness CORE weight management - no change from day to day) and a small amount of exercise (any increase bottomed her blood glucose level while we were stabilizing her). The amount of insulin needed had to be tapered back until we finally had to stop it. Unfortunately, changes had already been significant in her eyes prior to arrival, so cataracts were removed to avoid future complications. She arrived more than three years ago. Was off insulin within half a year.
Handsome boy! I don't see any basenji, though. If you would like to do a DNA test for health that also tests for breeds, Embark, which is affiliated with Cornell University, is an option.
I hope you have a patient vet and that your boy learns to settle down and be cooperative there. I've had dozens of fosters who started out as real challenges for the vets, yet they all got over it and became good citizens with the vets. They don't necessarily love the visits, but they cooperate calmly.
For no-see'ums in Florida, I use white vinegar and water, 50-50 mix. It works for about an hour or so. I keep a spray bottle outside with me when working with horses, who I also spray. I do wish it would last longer, since one of my horses is extremely sensitive to the no-see'ums who don't seem to be bothered by fly sprays for horses. The white vinegar mix gives him better protection for the hour or so that it lasts. For the dogs, I've sprayed my hand, then wiped the dogs. I do have a couple of dogs who are very sensitive to bites and a few who are sensitive to most of the other repellency options, so, though more labour-intensive for the number of dogs I have, white vinegar has been the one thing I can use to help everyone.