I have a covered litter box in our office. I dislike this box, but it's Benny's preferred box. (Once I removed and replace with an uncovered box, and was "rewarded" with sprays on the wall. . )
I use puppy pads under and on the back of the box. I also use a large floor towel in front of the other box to catch litter and "butt overhang."
I read about this waterproof fabric on a cat forum. The poster gave me the link, and I ordered two yards of it from Amazon.
I had some cotton napkins I'd bought at Goodwill, and sewed the fabric to the back of some.
The "fabric" was a bit difficult to work with, and I honestly wasn't sure how it could hold up in the wash. But, it works wonderfully!
I could see using these in the carrier, in case of an accident, or under water bowls to catch spills.