"I know being in a crate and driving around with us will be the first order of business"
I agree with Al U. Minium: introduce the cat to the trailer while it's parked.
Let him explore, find safe hidey-holes, and get used to the new smells. Bring in a favorite blanket or cushion, so there will be something comfortingly familiar. And of course provide food and water and a litter pan.
Bring a favorite toy. He probably won't play with it at first, but when he does, you'll know that he's feeling comfortable with the new arrangements. While he's exploring, you can sit inside the trailer and read or browse the web, so there'll be a familiar human present for reassurance.
Start with an hour's visit, then work up to longer periods over a week or two.
As for crate travel... here's what I do, for what it's worth. I have a folding soft crate
that I keep in the rear seat area of my pickup. It's large enough to hold food and water dishes and a small litter pan
. But my cat doesn't like being cooped up that way, and complains about it. So normally I let her ride in the trailer. She has a cushioned nest under the bed where she stays while I'm underway, and only she comes out after I've been parked for a while. The only time I put her in the crate is in hot weather, when the trailer gets hot while underway, with no open vents or windows and no air conditioning. Then she rides in the crate, where the truck's air conditioner keeps her from overheating.