My trailer (admittedly stick, but fiberglass) has been sitting in the driveway and gets splattered every day with the lawn sprinklers. Now I have harder than hard water spots on one side. Any great ideas for removing them. I've tried the household products and Gelcoat but they remain.
I had the same problem. I solved it by buying a gallon of vinegar and soaking a towel with it and letting it soak for several hours on the water spots. I used one of those green scratchless scrubber pads that are made for teflon pots and scrubbed the spots off.
A few of the spot seemed to be etched into the finish but after a good wax job they did not show.