I agree with what people said. Depends on the cat(s). We spent a winter in AZ with our 3 cats who are all related - GrMa, mom, & son - plus our 2 toy dogs. It wasn't easy. We took in the homeless cats & love them but it would have been easier not to have them along. We had no one to leave them with & couldn't afford 4 mos of boarding. We only told the park about the 2 dogs & were afraid we'd be kicked out the whole time. Husband made us keep our blinds closed. I bought 3 BIG canvas kennels & we took each cat for a ride in the RV alone in prep. They howled but we figured it wouldn't last. When we actually took off for AZ, each was in their own kennel. We let them out one at a time. I was afraid they'd freak & one would get under the gas pedal but it didn't happen. The son shredded his mesh windows on the kennel so that was $50 down the drain. I should have had him in a hard plastic one but I didn't know he'd do that. My worst fear was that they'd fight over the ONE cat box. At home we have 3 cat boxes for 3 cats but in the Class C, we only had room for one box. They didn't fight over it which was good. But I worried constantly that kitty litter would get in the slide mechanism.
We bought a little shop vac & cleaned the box every time it was used. Slide still works. The two worst things that happened were one of the cats, the only feral one, slashed our chihuahua & caused a blood bath. Our poor dog now has a split ear. It happened at night & she bled EVERYWHERE in our brand new RV - - walls, curtains, our clothes, floor. We finally got the bleeding stopped with compression of a maxipad we use for the chi's diaper (she's elderly) and antibiotic ointment. The other bad thing is the GrMa cat escaped. We were beside ourselves. Searched for 30 min & husb found her on premesis. Dogs are chipped & they were with us 24/7 but we don't have the cats chipped. She was hurt quite badly - - ran along a cinderblock wall & having been indoors only for years, her foot pads were bleeding. It took many days for her to heal. She actually has since escaped our stick home once since we got back too. We were so grateful a coyote, rattlesnake, or cactus didn't get her as we heard all these horror stories as we searched the park.
We are begging & paying our daughter this next season to watch two of them. She refused on this trip so I hope she doesn't change her mind. We think we'll bring the GrMa. I will keep the water bottle outside the RV & aimed as someone suggested. But that is hard when you are also escorting a Sr Dog & carrying groceries! One of the reasons I wanted an RV for 10 yrs was to travel with our pets because it's so hard to leave them. But I found that having our pets along took a lot of fun out of the trip. The dogs barked at everyone so we felt we couldn't sit outside much. The dogs are 11 & 8. The chi is 11 & she has heart failure too so has to be carried in & out, poor thing. The cats are 8, 7, 6. They each found a favorite place. Didn't yowl once they were out of the kennels. A couple liked sleeping behind the sofa. I brought pet beds galore. Had them spread thru out & each pet chose a favorite bed. There was a lady there who traveled with 2 cats & she had their furniture up on the dashboard. Actually let them out loose, which I wonder if someone complained about because a coyote could have killed them.
Long story short, it's a mixed bag. You would definitely want to bring a 1st aid kit & take a test run. Bring the cat's familiar items. Let us know how you do. I was never so grateful to get home & have space for them all to roam. Almost don't look forward to going again. I was an idiot to have 5 pets. Husb won't let me re-home any of the cats so now we're stuck with this mess. One cat should be a breeze!