After being gone 3 weeks last summer, and coming home to our (then) 12 yr old indoor/outdoor cat who made it clear she did not like being left behind, we decided to try taking her camping. We took her on several long weekend trips last fall and winter where we stayed in one spot for the duration; just returned from a 2-week trip where we moved throughout the state every couple of days.
We made the decision to keep her crated while moving after the first couple of trips being uncrated-she was so scared, always trying to find a safe spot in the truck. The last 2 trips she stayed crated on the armrest between driver and front passenger seats, and has settled down to sleeping through the drives. The only time she is unsettled is when the road is rough, or we play a book on tape--she seems to prefer our voices.
DH installed a cat door in end of the dinette bench, and put the litter box inside so she can get to it, but it doesn't occupy any floor space in the TT.
She likes to sleep under the jack-knife sofa, but was clawing the back to get out--we now prop the sofa seat up so she has access without the damage.
She is an early riser, so we are, too. She sleeps on one of the recliners or near my head at night.
We have done short stints with the harness, but he is not yet used to it. She had one anxiety-producing adventure in a catio-she hated not being able to get out. We need to learn how to make that a better experience.
Short story--she wants to be with us, and she has adapted bit by bit. We still have some learning to do to make longer travel and trailer life friendlier for her.