Sawbuck... I feel your pain.
Nancy and I used CLEAR silicone to seal the exterior areas permanently. at OUR SPECIFICATIONS. This would be OVER any Airstream sealants, applied at the Factory.
The shiny one inch wide strips, with rivets, is a lot of feet to seal. Sealer is cheap... my time is cheaper.
It is sparse around those Tail Lights.
The gasket is thin between the tail lights and aluminum body. We have done all of the sides, front and rear. Checked the windows, which are so far, fine. We are going to Silicone those today... thanks for a heads up.
When we took the Airstream Tour in 2007 at Jackson Center... they had this area where the Shell would have a huge amount of water dumped upon it. If it leaked... they missed it as it would have been in between the outer and inner skins.
Yep... I had to suck up the 2019 FB27 Front Storage Compartment getting splits / indents.
My fault... of course.

After beating and trashing my other Airstreams as I am a Beast and a Neanderthal. Nancy is a Human Bean. Keeps me on a loose leash.
I purchased an Oliver. It is also a 2019. Oliver made their #1000 this month. Ours is below 500th. No leaks. No cracks in the fiber glass. No problems. We will give the Oliver a test this year. The previous owner did the same travel as we do.
He was a Human Bean... but I know he is a Neanderthal.