Class C or TT to RV with cats? Crate or no crate?

We have travelled with our two cats quite a lot.

We have a crate in the truck for them. While in the City limits, they are in the crate. This is due to the higher probability that we will be opening doors and/or windows.

Once on the highway, we open the crate. One of the cats likes to sit between us and the other sleeps on top of the crate.

Right before we get out of the truck for set up, they go back into the crate.