With my rabbit Lucy who was large we tried multiple things when it came to litter/bathroom. We had a rabbit litter box which was too small, we used a covered cat litter box, a regular litter box, the Morton box which worked great but we ended up having a large cage with a built in pan. It was a pain. I highly preferred the Morton pan. There is a website I am getting my new bunny from and they build litter pans. Basically it is rabbit wire that is secured in a tray placed over/in a typical cat pan. Bailey bunny farm is the name of the website if you want to look. Lucy was really not very well potty trained. She really did best in her large dog crate with an x pen hooked up. I know it stinks but sometimes give things a chance and try something new. I saw a post recent showing a photo near the litter pan before getting “fixed” and a few weeks after and it was a big difference.