RJ - I'm not sure if you want photos of actual existing Airstream
installations - or info on potential options for installation? But here is
a model for potential consideration for installation in small trailers.
It's designed for small trailers/tent-campers/camper vans etc - and is
designed to be an "off-roof" installation. - and - it's a heat pump design
so it offers some heating capability.
It refers to it as an under counter installation. Interior air
distribution is from the front of the unit or via ducting. It does not
mention what it's exterior venting requirements/limitations etc. are.
Duo-Therm Cool Cat
http://www.advrv.com/ac.htm
I hope this adds to your input.
RL