The rule around here is if we go, the cats go. We have had cats since 1964.
The first one was while we were in college and our only transportation was a motorcycle. He liked to sit in the big pocket of my windbreaker or the right saddlebag. He would sit on the seat of the motorcycle waiting for someone to go somewhere so he could tag along.
All subsequent going places close and not so close have been in combinations of cars and rvs. All of the cats had their quirks. Some loved being in the over the cab spaces so they could oversee things inside and out. One seemed to object to the first night out. If you are traveling for time in an rv, each night until you arrive at your destination is the first night out. That cat was an 18 pound male ragdoll (breed) and a sweetheart but he had a voice that would curl your hair and he would spend that first night yowling and stamping all over my husband. The following morning was not fun at the breakfast table. We discovered that if Rich slept over the cab that first night and the cat and I slept in the bed, all was right with the world from then on - even at the breakfast table.
All but one of our cats lived to very old ages. A couple of them were diabetic, complete with meters, blood tests and insulin. They went with us also. One other cat had a special diet I needed to make for him and he and his diet and his equipment went from Florida all over the Midwest and the northern Midwest for four months one year.
I guess that means that if you want to do it, it is doable? Your idea of a 'warm up/test' trip is a good one. Away from home, I would think. Every year we have the rv gone over for problems and then pack up and spend a week about 30 miles away from home so we can be sure everything and everybody are on track and everything and everybody can be towed back home in case of problems that did not get taken care of.
Oh! Before you head out for somewhere for real, make sure everyone, including the people, has had the doctor's/the vet's once over gently, all meds are covered, there is a list of what meds for whom, why, and phone numbers for doctors and vets. Not to mention critter shot records. People shot records would probably help too. We have been in emergency situations with both cats and human and the above is really important.
Enjoy your get away. Sorry for the length but I was a project manager and one of my quirks is that I despise unnecessary and nasty surprises. "Plan for the Worst" is my motto because, if you do, everything else is a piece of cake.