Had cats for many years. One of the things we did find useful was to get a large cardboard box - bigger than the litter box - to set the litterbox in. We cut a big u-shaped entry in the side for the cat(s) to easily access the box (no lid on the box). For some reason, one of the kitties seems to have found that preferable to just having a litterbox in the corner and would then always use the litterbox, whereas before we would sometimes catch her pooping just outside it. So yeah, I made the cat(s) a privacy screen. It did work for us. Also always left just a tiny bit of the soiled litter in the box so it was like marking "the spot" - not enough for us to smell, mind you. Just for the cats to ID. Glad your kitty is sorted out now!