Howdy and welcome to Airforums.com, Morgan guy! You are in the right spot to explore all subjects related to Airstream trailers.
Wow, that certainly IS an interesting trailer. Do you have any way of proving the provenance (Rex Rossi's ownership)? If so, then it would be good to mention that in your ad when you sell. it, many people value trailers more highly if interesting previous owners can be established.
I'm sure that I saw lots of Rex Rossi's work; Hopalong Cassidy was THE hero in my life in my early days. I bugged my mom until she finally got me a complete outfit of his. TV was new then, and so was I, so it never occurred that ole Hoppy wasn't doing all those crazy things himself.
Why not post some photos of your trailers? We'd love to see them...