I came across a series of YouTube videos of a guying doing a shell off restoration of a 1979 Ambassador, I donít who knows about them here but I thought you might be interested in these YouTube Videos. There is several of them showing results of welding up the frame with lots of steel. fixing out riggers sand blasting etc,
He is using a Farm Tec polyethylene plastic product for his replacement floor. There are several videos here is a few you can find the rest from here.
Airstream shell removal - YouTube
Airstream frame shell off - YouTube
Airstream plastic floor - YouTube
The one on the polyethylene plastic product might be part of the answer to the Upgrading floor material post earlier this week
Rogue River Oregon