I came across an old, black, tubular car barrier I used when I had my Siberians. I prefer to keep Mardi in a crate in the car so I have not used the barrier and it was just left out in the garage. I noticed it today and brought it inside. I had purchased an extra section because my Matrix is a tall car so there are three tiers of double bars. Everything is adjustable and I have the bottom opening at 7 inches from the floor. The cats slip under easily and Mardi hasn't tried to squeeze her skinny body under. It isn't pretty but I think it is going to work.
What is it about dogs and litter boxes?? Yuck! Glad you found a solution.
Sounds like a plan to me!
Seamus and Flynn