Here's an idea... make a really big mould off of the Airstream, use it to build a fiberglass shell, mount the shell on the Airstream frame and fill it with all of the Airstream's interior! Then you have the desired size and floorplan features, without the million rivets!
Just kidding, of course. Zeb has systematically considered the alternatives, and given us some food for thought in the process. The choice is not one of "ours", but having that choice is important.
Best wishes, Zeb.