Back in the early 1970's, I worked with a guy in Virginia who had been an engineer at Open Road, down in Florida. OR often had their engineers drive a new rig to a dealership, to give them some experience driving what they were designing.
Dave recalled taking a Chevy-based Class C to a dealership in San Diego. The bare chassis had been driven from Detroit to Florida, then driven to different suppliers locally for things to be installed (they had Midas put the exhaust system on) By the time he left Florida, the rig already had 2200 miles on the odometer. By the time it got to the dealership, it was pushing towards 6000!
Dave's group looked into shipment by rail to minimize the accumulation of road miles. They put two new rigs (a Class A and a Class C) on a low-loader railcar and sent them from Florida to Chicago. Dave and his boss went to bring the rigs back for evaluation. When they opened the rig doors in Chicago, the entire interiors of both had collapsed into matchwood in a big heap on the floor.
I think they got the truck chassis shipped by rail a few times, but the suspensions were so beat up on arrival, they quit doing that also.