At least one vet I know has scale/tables mounted to the wall that can be moved up/down for different sized "clients". Does, or would, that help in combination with a proper chair/stool with back support that also can be height adjusted? Just a thought. I'll do some more thinking and ask around.
I have to do pretty much what you do -- bend over.
I'm curious about back supports myself. I've asked my doctor about them, and he seems to think they're of no benefit, but I've heard some guys swear by them.
Doc