There is an installation video from a sponsored project from GoPower Solar at
1960 Airstream Ambassador Blog! | Hosted by The Vintage Airstream Podcast
Installation of their product on an Airstream that is interesting. Looking a bit more I was recommended towards AM Solar and have an estimate of a 3 panels @ 135W each as complete install for about $4200 in California.
Lewster has some advice on power loss from panels that is interesting and recommends the AM Solar as more efficient in that regard. Generators do work, wonder why Airstream does not offer an installation unit?