We travel with 2 cats (now 14+ y.o.) who were accustomed to living in an apartment, so they transitioned easily to our 26' Class C.
Whenever I started the ignition, Clyde would climb behind the sofa bed on a space behind the backrest, and stay there until either I shut off the motor or his bladder gave notice. Bonnie, on the other hand, would stand next to the "doghouse" (pardon the insult, kids) console and look up at us, asking permission for a lap -- usually mine, between me and the steering wheel, and later moving to my door's armrest, with my arm resting on her!
We use a litter box with a double-height barrier to prevent spillage, and kept it between the sofa bed and my seat back. With a food and a water dish secured on the sink counter during travel, they could do as they wished.
CUTE STORY: Because we use a wheelchair lift on the rear doors -- which, therefore, stay open until we enter and fold up the lift -- we had a double-wide bathroom door installed, that would block the entire hallway space between the cabinets on either side. We thought that this "airlock" would keep the little "monsters" inside.
But, the first time we went away for a few hours, when we opened the back doors, there were Bonnie & Clyde, each perched on one of the lift platform extensions, saying "We missed you, Mommy & Daddy"! This meant that I had to race in from the front door, open the hallway door, and bring them inside so that DW could open the lift.
Apparently, our 2 acrobats had gone from the sofa armrest to the sink, hopped onto the top of the door (3" wide and about 3" below the A/C vent shroud), and done a 1 1/2 gainer in the pike position to make their grand entrance!
We then had another portion added to the top of the door, so they didn't have space under the A/C any more.