Our cats travel in the truck with us in carriers that are strapped down between the dog beds. Our two old boys were so bonded they had to be in the same carrier, but the two new girls want separate accommodations. At all times they travel to and from in their carriers.
Since we have an elderly dog, we stop every couple of hours for pee breaks (canine and human) and the cats are let loose in the 5er to have a drink and a pee break if they want one.
In the truck, Luna (longhaired tortie) fusses once or twice and then settles down for a nap. Lili (siamese) expresses her displeasure at regular intervals. (good thing I really love siamese!)
Both cats treat the RV like home, and love the new channels on Cat TV when we stop.
I am much happier now that we located a space behind a cabinet that had an outside access door and moved the litter box there. DH put a cat door into the side of the cabinet that we can close off when cleaning the litterbox and enclosed the area so they cats do not have access to the rest of the basement. The exterior hatch is locked at all times to prevent any accidental openings. I just have to be sure that there is not a cat *in* the litterbox when I close the cat door, otherwise, we both have a surprise when I open the hatch!