Dale, there are a number of good waxes out there that also have UV protection for sun damage. Meguiars is one and is available from westmarine.com
. We treat our Casita's like they are boats being stored outside and use marine supplies for maintaining that nice coat. Hubby and I believe that several light
coats of wax are better than one heavy one, but the key is to get a good marine wax on it asap. We usually wash and wax twice a year and our trailers are covered in the winter time.
With a nice wax job on it, you can just rinse off the dust that accumulates and you don't have to worry about sun damage either. If you end up going with a cover be sure to get one that is breathable...who knew that fiberglass needs to breathe, but it does.
Best of luck with your Scamp and may you have many days of enjoyment with it!