How about carpet tiles? They have really thick rubber backs and a low pile that makes it tough for buns to pull the fibers out of, even for my bun who has eaten all my other rugs. If they do pee on them, the rubber back keeps it from soaking through to the floor and damaging the floor. I have a few extra tiles and when one gets soiled, I switch it out and take the soiled one out back to hose off with a bit of soap, though car washes are amazing for this kind of thing, too, then let it dry. The best part is they’re super cheap at closeout type stores (Big Lots, Ollie’s Bargain Outlet, etc), so you can afford to have a few spares and you can cut them to whatever size you need. Under my bunnies’ cage, I have a cheap vinyl tablecloth covered with carpet tiles just in case the moisture would soak through if there was an accident and in case they shift around a little, but overall they work really well.