Glad to hear you made it home in one piece
I brought one in that was losing pieces all the way home
Don't worry about walbernizeing or clear coating at this point, it is probably a lost cause
what you have now is refered to as APB (Airstream Pattern Baldness)...and there is no known cure
But if you really want Walbernize stuff it is available from local Airstream Dealers or www.airstream.com
look for it in the store. As far as the windows...if you are lucky and no one has used silicone on them, you can clean out the old caulk and reseal with Vulkem, again it is available from several sources, www.airstream.com
and possibly your local home center or commercial roofing supply house.
I would also re do the plumbing vents ASAP, they will need a rubber gasket and some fiberglass screening to do properly. If you need specfics email or PM me, or run a board search. Another suspect area is around the TV antenna, Air Conditoner, running lights, roof vents, and anywhere else there is a penetration of the skin.
BTW which 75 model did you end up with? And did you get a Service manual with it? If not let me know, I have one and will be glad to provide a scanned copy for you. Us 75 owners need to stick together