What may help is:
- don't tower over the dog and stand right in front of him or look him in the eye directly; sit on your hunches beside him, facing the same direction and be calm;
- offer the collar and a treat just in front of it, so he has an incentive to put his head forward into the collar.
Well, if you don't want your dog to want to be with you all the time, think again. Basenjis can be true velcro-beings, ours are, especially when you locate yourself on a chair or couch, behind your laptop, or in bed. During walks, our two sisters do their thing, but always keep an eye out for me, and follow immediately when I change direction. And they do respond well to recall signs and sounds, especially when the plastic bag with treats comes out. It seems, the calmer I am, the less I say or do, the more they stay around. All in all, I wouldn't have it any other way.
Some dogs are more cuddly than others. And maybe this boy needs more time. I know of cases where it took one to two years for a basenji to invite and enjoy cuddles. Patience is key, and along the way, try to seperate your own needs from what he needs. He obviously sees you as the leader, so you have done a lot already. Take pride and joy in that. He will come for more if and when he wants it. And kudos to you and your family to take them in.
An apartment would not be a problem if you give your B plenty of exercise and nose time. Also, the office would be great, but do realise that dogs need a lot of sleep, not only puppies. Our 2 sisters (7 and 6) sleep all night and most of the day. So your B would need a quiet space in the office to retreat and sleep. Agree with eeeefarm: puppy time is extra intensive, but so much fun. Try to be with your B as much as possible. Enjoy!