I have a geriatric bunny (11 years) who is having difficulties getting to in and out of the litter box, sometimes when he is not feeling well he will pee in his bed and it gets him all wet. Urine Scald can be a significant issue for disabled rabbits. Wire bottom cages simply trade one negative scenario for another, so wire floors are not a viable option. As vegetarians rabbit poop from all but a very sick bunny consists of dry pellets so is not a significant concern if moisture in the environment is controlled.
I am looking for solution(s) for house rabbits, but solutions that are not species specific are welcomed.