Greetings alberta paso!
Welcome to the Forums and the world of Vintage Airstreams and Argosys!
From your description, it sounds like the rear galvanized steel endcap is damaged and would likely require replacement -- a major undertaking and it is highly unlikely that a new replacement could be located. Depending upon the extent of the damage, an auto body shop may
be able to repair the existing endcap. The interior endcap is likely damaged to the extent that repairs would be quite difficult and finding a replacement could be difficult -- so the likely solution would be to form fanned panels of aluminum to take its place. You may also find that ribs would need to be replaced. Making these repairs would likely require, at a minimum, removing the rear bathroom furniture/fixtures to facilitate repairs.
Patching a puncture in the roof would be more direct and less involved so long as it didn't include a dent as well as the puncture. The key to the repair would be to utilize well sealed patch panel with sealed rivets. The same would be true of replacing the roof vent. It would be rather straight forward provided the roof wasn't dented when the vent was damaged -- you might get by with simply replacing the cover -- or you could upgrade to a Fantastic Vent as many do when replacing the original vents.
Replacing the rear window would only pose a problem if the frame is damaged in any way. The window is readily available flat glass (I believe tempered, but am not certain) that a full-service glass shop could likely cut and install into your frame. If the frame is damaged, locating the replacement could be time consuming as I am not sure as to whether this type window is available from Airstream any longer.
If the original axles haven't been replaced, you can anticipate that they will need replacement. Unless the current owner can provide proof of age for the tires, it would be prudent to install new tires before towing the distance you would be embarking upon. Servicing the bearings and checking the electric trailer brakes would also be highly advisable prior to embarking upon a trip of the distance you mention. You can tow the trailer with axles that are essentially worn out, it is, however, advisable to limit your towing speed and try to slow down for rough road sections, rail crossings, etc.
Whether the coach is worth restoring is a question that only you can answer, but some considerations would include:
- Beyond the damage mentioned, has water infiltrated through the opening adding to the destruction?
- Is there significant rot in the floors?
- Do you plan an entire gut remodel or do you want to restore?
- If you don't plan to have body repairs handled by a professional, do you have skills need to perform the aluminum/galvanized steel repairs?
- What level of perfection do you want in the final product? A higher degree of perfection will be easier to achieve with a coach having little or no body damage.
The coach that you describe would be a MAJOR project, but there have been others on the Forum who have completed similar challenges.
Good luck with your investigation!