I bought my RV a few weeks ago for the purpose of bringing my cat with me on my next out-of-state job. (I have to follow work right now, as a seasonal park guide/interpreter. I spent one miserable summer without her and met some full-time RVers who gave me the idea.)
Anyway, I finally got it all set up in my parents' backyard, and Lily got a look inside. We're spending the night here. It's a Wildwood 26TBSS, which I chose specifically for the potential to set up the bunks as a "pet corner." Lily slunk around investigating at first, but she found the soft bunk and open window and settled in happily. She joined me in the bedroom to watch TV later. All-in-all, Lily is a very happy camper.
(And she hasn't showed any interest in the door, open or closed. She's an indoor cat and has never been really interested in getting outside.)