All repairs have been made, wraps and belly pan reinstalled. Looking at the trailer you would never know I did anything, aside form painting the hitch.
So now I want to seal the area where the hitch penetrates the wrap, and I've had no suggestions so I want to revive the topic and see if I get anything useful.
There were some plastic trim pieces, L-shaped cross section, bent in a U-shape (with square corners) that dropped over the hitch frame, snugged up against the shell and were pop riveted in place. One is mostly intact, the second is broken with a large piece missing. I have contacted Airstream for parts and this piece is no longer available.
Right now I am considering trying to repair the broken piece, splicing in some new plastic with solvent glue or plastic welding, then before installing, coating the backside of the flange with vulkum.
Still looking for suggestions...
BTW, the exposing of the frame, making minor repairs, painting, replacing insulation, etc, it was no fun at all. However, I did the rear section several years ago so I had a good idea of what I was getting into. Like the rear section, I am glad I got in there when I did. This type of project, when done properly is likely a once in a lifetime job.
Its a camper, therefore it leaks.