Our condolences on the loss of your friend. Never easy.
You can celebrate the recreation of an Airstream. All new frame, subfloor, insulation, tanks, belly pan, wheel wells, axle, etc, etc. It will have "good bones" to support the shell and the new interior.
I trust the riveting will go well. You guys will be like Airstream employees. Rosie the Rivetor? Someone has to hold the bucking bar while the other bangs the rivets tight. Two person job. I'm sure all the work involved in making the shell is one of the reasons why Airstreams are so expensive.
Thanks for the update. Congratulations on the all important, newly fabricated "bottom end" of your Globetrotter. Now on to all the wiring, fresh water plumbing, seem sealing, window repairs, cabinet making, and on and on. It's a huge project.
Maybe next summer you'll be camping on the shore of your favorite lake in your "new" Airstream. Others will stop by and ask to take a picture of your trailer.