You might try a google search for a 1980 Wilderness (include model number) to find any paperwork or manuals for it.
If it is in halfways decent shape it might be a fun project.
We had a 1978 Coachman Cadet 24-foot travel trailer that we bought used in 2000 and it was basically beyond any kind of affordable restoration, but we made the best of it for 13 years before we traded it in for $200 less than we paid for it.
It was usually (but not always) the ugliest and most beat up trailer in the campground.
I did resurface the roof as it leaked like a sieve . . . nothing worked in it except for the electric and the furnace.
The black and gray tanks leaked . . . my father-in-law tried to patch them but it proved to be a futile endeavor.
And since we couldn't use the plumbing, the bathtub was the perfect place for our coolers as the refrigerator didn't work (we used it as a pantry instead).
The frame was bent and was even cracked and separated by the entrance door (I always had to jack up the front door side corner a little high just so the entrance door would open) and the trailer brakes only worked going up hill . . . not down hill when needed the most!
Be we sure had a lot of fun with that old beast . . . I miss it sometimes (but DON'T want it back).
We called it our 'tent on wheels' and I was about to name it
'Trailer Trash' and have that painted on the back like boat owners do . . .
That is when we decided to move on and get a brand new travel trailer . . . and now a 5th-wheeler.
Here it is:
The beauty of it was that I wasn't afraid to take it anywhere since is was already beat to heck.