I am not really familiar with your vintage of Airstream... ours is a 1963
and the interior end caps both front and rear are fiberglass. I am clueless if yours is, but if you describe it as plastic stuff... that would be my guess. Our bathroom area is largely fiberglass on the top curved part. Is that the section you are thinking about? Is your bath in the back?
You can repair torn fiberglass but you might need assistance from someone who has done fiberglass repair. You might look locally at a auto restorer that works on fiberglass car bodies and talk to them about the best approach for repair. I have never done any myself, but my husband has. It seems you can get a kit from the auto stores with a fabric that you put over tears,etc. then re-glass over that. Lots of sanding, painting, etc.
I see you have posted other questions, but haven't got answers yet... hummm very unusual. Another option would be to read the information under the names of people posting to see what year Airstream they have and when you find someone with a early 70's Safari you might send them a personal message and ask if they have suggestions. If you click on members list at the top blue bar you might get that info. There should be a little Personal Message link on the page somewhere... (sorry that isn't much help)
One of the things we did early on was to attend a rally and meet many of the Airstreamers. Great thing to do. Usually at a rally you can ask lots of questions to the guys/gals that are the do-it-yourselfers! Found out lots of useful things. Click the rally schedule button at the top and go through the calendar... might be useful for you as well.
To post a picture if you make a written post~click the advanced button and then, just below the rows of post icons at the bottom of the page you will see "additonal options" in a blue bar (scroll down if you don't see it)Then you will see a gray button that says manage attachments. You can click on that and upload a picture from your computer or digital camera.
Good luck! See if you can figure out if it is fiberglass...
Mrs. NorCal Bambi (traveling in S Tardis)