As far as the cat food goes, you might just designate a high spot to feed the cat. My cat eats in my utility room on top of the dryer, where the dogs can't reach her bowl. As for the litter box, I think the baby gate is a perfect idea, even if you use a closet or bathroom to keep it in. Just keep the door cracked a little. Our litter box, which our cat doesn't use a lot, is in my bathroom, which has a bi-fold door. I have just had to train myself to keep it cracked, just enough for Mimi to get in. Good luck.