We had a cat that loved to camp with us. We took a litter box that was in the back seat of the truck while we traveled. On the other side of the seat was a box with his blanky on for him to lay on and look out the window.
He was always on a leash in case he tried to get out when the door was open and we wanted to grab the leash and stop him. When husband got out to get gas he sat on my lap.
He learned to go for walks at the campground, sat on his own chair by the fire and every night about eleven he would go the the TT door and ask to go for a walk. When we went to the door he would sit on his leash so we take him.
The one problem with walking him was when he decided he needed to use the litter box he would make a mad dash for for the TT pulling me behind him.
Opie was twelve when he went camping for the first time so you can teach an old cat new tricks.
Opie howled the first ten miles of any trip and then settled down. I think he knew then that we were not going to the vet.