Originally Posted by Airtandem
what about using Kool Seal both inside and out? It's flexable.
Kool Seal makes a variety of products, not all of which are necessarily flexible. And they're not designed for use on moving objects; they're designed specifically for flat roofs or low-slope roofs on commercial buildings. And they're not designed for inside use, either.
They make a product specifically for aluminum roofs, but it's an asphaltic coating which would be ugly as sin on the roof of your Airstream.
Their flexible coatings— the elastomers— are very fragile. If you brush your Airstream's roof with a low-hanging limb, you'll tear the elastomeric coating to shreds. Their elastomeric coating is nothing much more than a spray-on or brush-on roof condom.