Polymetal?
It comes in 5x10 and 4x12 sheets. With an adequately large roller you could radius it lengthwise.
Your suggestion at
http://ecomodder.com/forum/showthrea...tml#post568521 for SingCore is good. For interior partitions, etc.
There's also
swing door material for the deck.
Getting away from aluminum, there would be
basalt cloth in
Super Sap epoxy, for the end caps.
The Airstream shell needs Faschenfeld tearing edges, something like this:
That's actually closer to the Airstream Basecamp than the classic trailer.
I always thought the Saprtans were upscale to Airstream, but I just learned about Palace:
Just A Car Guy: The Palace Royale