You can try a wax or the like, there is a bunch of them on the market, with good recommendations here on F.B.R.V. but...
in a scamp
this old? I will answer no
...There is nothing you can really effectively do
...The gel-coat takes the brunt of all the environmental impacts on the trailer and its only couple of trash bags thick, in its era NO U.V
. protection was available in the common market...So...Its well washing off mil by mil.
Add to this issue it ages at a set rate and deteriorates as a part of its function, and you get the picture, like dead skin coming off when its use is over.
In a nut shell its time to go to work, do your research, get the pennies together, budget 3X as much as you think and 5X as much time...Keep a serious sense of humor on hand and post your issues, triumphs and set backs to the fiberglass voyeurs here...We like pictures....
Now that honesty has answered the question, let me say this...You love the thing or you don't...The project at hand will be part of the story of this trailer and you as a positive, or get out while you have cash...Envision if this trailer will be part of your lives for many years or you can pitch it out for a project for another enthusiast...There will be takers a plenty, you can get one you can squeeze more use out of if its in better shape.
If you have a location to work on it, my vote is to go for it, the project will teach allot and afterwards the trailer will reward you with the memories of a lifetime.
There are new products on the market that make this much easier, many have been intrepid enough to attempt it and the results are beautiful.
Happy Camping, Safe Trails.