+1 on the salt decay being a major concern. if it was just water rust from sitting in a field or cold shed or barn or from being under a plastic tarp, then that is one thing. Road salt or calcium is quite another matter. Any possibility you could grind them down a hundred or so?? I know, I know, yard wants to make a profit, but in this case, that profit is more likely to be based on the uniqueness of the construct rather than high demand. Sad to say, if they will clip the rear off at the back cabin mounts then that might be the way to go.
Nick
Nick