Do many people look at engine hours on a combine? I doubt they will have the separator engaged for the trip. 35-40 extra engine hours in the long run isn't very much.The hours you will put on combine x $x/ hr depreciation might be very close to your trucking quote. Then there's the insurance factor, if something terrible happens. Trucking companies carry insurance and that combine is alot safer ( from idiots)on a trailer doing the speed limit.
A relative of mine (Canadian tryingto enter US) was turned around at U.S. border a month ago. He was going down for business (agricultural).