I am so sorry that you have had all these difficulties and you've certainly been very patient to try to solve his problems without professional help.
However whatever you do, please, please find a Basenji qualified behaviourist. So many who have little knowledge of primitive breeds make the most horrendous mistakes and can, therefore, make matters worse.
I'm assuming you're in the USA where in my opinion you'll be able to find a suitable person. In the UK, it has become increasingly difficult to find a Basenji knowledgeable behaviourist. Although I'm well versed in Basenjis, I'm unwilling to offer any tips about his behaviour as I haven't seen your boy.
I sincerely wish you success in improving his and your lives.
I had a basenji bitch who would never tolerate being shut in a crate. She even got out of a padlocked crate by collapsing it around her and climbing out! Ziggy is obviously smart and my answer would be never to crate him but leave him in a safe room from which anything destructible is already removed.
If he has doggy company even better and as Pawla suggested tire him out. Give him plenty of long interesting walks and leave him with toys etc. I hope that he isn't left alone for too long particularly while he is so young - he may improve when he is older or more accustomed to being left for shorter intervals.
It would be ideal to have somebody you trust to look in on him and take him out for comfort walks.
I don't think she has Basenji in her make-up but she's lovely. I am more au fait with Basenjis than other dogs so couldn't really guess her make-up. Be warned though that as soon as a dog of unknown origins has a curly tail and facial wrinkles people assume Basenji. If you desperately need to know, a DNA test could be the answer but I'm sure you love her whatever (and no wonder!).
With training, the aggressive growl will most likely disappear. I would first get him very used to all members of the family encouraging him to accept giving up food etc. With your experience I expect you'll know how to do this. I really don't want to 'teach my grandmother to suck eggs' so if you need further advice on this please let me know.
I've reread your post to ensure that I'm sticking to your question and see that you are asking for a story but yes this is from personal experience. He has obviously allowed to get away with it so it'll take a long patient time.
Hugs to you both and best wishes for success.
He looks a beautiful dog and if you hadn't said, I would think what a friendly one. I can't see Basenji at all except perhaps his tail but there are many breeds with tails like that. Love him and give him lots of caresses. I haven't any experience of DNA kits so can't help there. Hugs to Harold and yourselves.
@roojuice Garlic spray is a good and effective repellent. As to the bites, homeopathic Apis Mel 30c effectively stops the itching in a very short time. For stings (non-insect) Urtica Mons 30c potency. Both of these are available at ainsworths .com and I suggest in soft tablet form. Avoid actually touching them when you administer - I tip one on to a clean piece of paper and my dogs will take them from there. To get Flash to eat them throw a few around when he'll probably pick one up and then find he likes the taste. You can then give him his proper dose on the paper.
@antigone - I do understand what you are saying. We are fortunate in the UK because meat free of steroids and antibiotics is more easily available. I know too how one can get into campaigning mode about issues they feel strongly about. However, like Harold I'm leaving this post now -we seem to have wandered a bit from his original post. Best wishes.