There have ben a few threads on this topic. Try the "search" feature and see what shows up. I know you have to stay away from the end caps! One thread I remember shows 2 trucks on either side of the airstream with ladders connecting the trucks over the roof making a scaffold to work from. There are other options, too. Good luck!
1962 16' Bambi (sold
1996 Buick Roadmaster Estate Wagon
Airforums# 7906, WBCCI #4248, WDCU