Oh yes, belly bands, also pee pads and also Bona wood floor cleaning products.
I have one dog, Dee, who was apparently paper-trained as a young dog and will not wake me at night if she needs to potty, but will go on a pee pad that is placed near the living-room door. So that, and generally cleanup of same, is now part of my routine, which was NOT my idea.
For old dogs, I don't know anything to do but build routines around their quirks and disabilities, and sometimes that's nearly impossible.
I find the refusal to walk on familiar routes interesting, because my sister's senior rescue Bearded Collie is doing that. There is no shifting him once he has taken against a walk route, and we have no idea WTF is going on there. Oliver is in good physical health, but the quirks he has had since he came to live with my sister at age 7 have intensified over the 5 years he's been with her.
Have you tried Chlomicalm for him? Once you sort through what he's currently taking and see if any of it should be discontinued, maybe consider adding this? It's used for SA quite a lot, and my vet also uses it for symptoms of senility or canine dementia. https://www.drugs.com/pro/clomicalm.html