Herewith are Four web sites offering the most Airstreams to look at, though by no means all there are... I Haven't included E-Bay, though they have some good ones, some fraudulent ones, and some wrecks described as "Good condition.."
1. The Classifieds here... Relatively high trust factor from long-term members, not so with new members...
2.
www.rvtraderonline.com Search for "Travel Trailers" and by brand for Airstream and Argosy. Limit to
1960 through 2001 to avoid new dealer listings...
3.
www.airstream.net Vintage Airstream site, but many trailers listed from 1970 to present...
4.
www.craigslist.com Series of free local web postings, but possible to search outside your own area. Not an auction, but opportunity to see pictures and exchange messages with seller directly
Rear Bedroom started with classic 25' floorplans of early Excellas, etc.. Others like new 19 and 22 offer rear bed, but with bathroom adjacent on street side of trailer, and often "Wet bath" where shower wets down entire area, including toilet and medicine cabinet...
With that truck, you could look at 24 to 29' trailers, and find some good deals, I suspect...
John McG