Hi Tiger Shark: Welcome to the vintage Airstream hobby. You have a big project ahead of you, and a fun one at that. Renovating these old Airstreams is a great hobby for me.
I have a 75 Overlander 27' which is a year older and 4' shorter than your Sovereign
. It was in pretty good shape when I bought it about a year ago. It had rear subfloor rot, some rear end separation, some frame rust, broken waste water tanks, bad axles, and old appliances that worked, but not the greatest. I have made some progress. The subfloor is repaired along with the rear end separation, the frame rust has been repaired, I have install new waste water tanks, I have replumbed the entire trailer fresh water and drain pipes, I have new axles waiting. I am currently reassembling the bathroom but summer activities have slowed me down.
You may like to start a "project thread" for your Sovereign
. Many folks use the Airstream Trailer Knowledgebase found near the bottom of the Forums page. Find Sovereign, and they your model year. You might enjoy reading some other threads on Sovereign rebuilds found in this area. And you may enjoy taking a look at my project thread in the Overlander section, 1975, link below. Our trailers are built pretty much alike.
Pictures are always interesting here.
WBCCI #8607 VAC Region 11
KnowledgeBase trailer renovation threads: 69 Globetrotter, 76 Sovereign, 75 Overlander, 66 Trade Wind Such fun !