I'd love to see a video of someone actually getting on an airstream with a ladder like you suggest. It'sounds a great idea in theory, or with a regular house, but i tried it once and it was far more dangerous, due to the curved edge of the airstream.
When the ladder extends 3 feet past the top, you need to be standing on your feet all the way up until you swing your legs over. That means standing on the slippery, curved edge of the airstream.
Whether OSHA approves of my method or not, I'm using it because it is far safer to me. I can scoot over on my butt and make sure I have a strong foothold before weighting the ladder.
One thing I should do, however, is tie a rope to it and secure it to something on top so it doesn't fall over while I'm up there.
