It appears that these are cracks in the gel coat, which is the first coat of colored fiberglass resin that is sprayed in to the mold. I do not know of any permanent repair that can be done.
You could sand and fill the cracks and then have the exterior painted, but I am sure that there would be no guaranty that new cracks will not appear below the paint.
This sounds like a factory defect, since everyone with a fiberglass sidewall coach does not have the same problem. On a 6 year old coach, that is long since out of warranty, I would not expect the factory to step up and acknowledge that there was a problem. Perhaps one of the decorative "wraps", that are now gaining popularity on auto's, trucks's, and RV's, may be one answer.