My grandparents traveled with two cats, one disliked being in a moving vehicle of any kind ( my fault but we won't get into that. The other loved it and would sit where he could look out the window like a dog, but as soon as you put him in a crate he howled till he was let out. Small litter box on the back floorboard or cargo area just in case. Always kept harnesses and tags on them just in case. A trip around the neighborhood with them loose should give you an idea how well they will travel out of a crate. They did always keep 2 folding soft sided crates packed for emergencies.
The cats will react the same while driving if in a c, or a TV. Like others have said it's really depends on your cats and how adaptable they are, and what works best for you.
After shopping around, getting lots of good advice on here and from my grandparents,and time weighing our needs, wants, and budget we decided on a small TT. With a C you have all the regular maintenance of a vehicle as well as well as all the regular maintenance that goes along with and RV.
Another thing to take into account is where you'll be doing most of your camping will you want to leave the campground for day trips around the area? If so with a C you would need to tow a car.
On the other hand in a C you have the ability ( if not driving) to move around ( use bathroom, make lunch, stretch out). Also you would probably have an onboard generator which gives you more freedom in stopping over at a Walmart or truck stop while traveling.
The best advice I got which was / was not helpful was it all comes down to your needs wants and budget.
Hope you and your cats enjoy your travels
