We have a pure bred Great Pyrenees and allow her to travel where she is comfortable. Our other Pyr, male, was the same way. Since yours is a mix of a lazy dog(Pyr) and a high energy dog(Border Collie) I would let your dog decide where it is the most comfortable and then move the dog's bed there and see how it does. Our Pyr is well over 100 pounds so a crate is out of the question because of it's size. I'm not sure how big the crate would have to be to comfortably allow a 70 pound dog to ride in your coach. Probably about the size of an RV couch.
Drooling comes with the Pyr since it is a "wet mouth" type breed so you may just want to keep plenty of towels in the RV when you travel.
It might take several trips for the dog to feel comfortable but remember Border Collies aren't known for wanting to lay still.