Waxing fiberglass with automotive wax may not necessarily harm the fiberglass finish, but marine waxes are formulated for gel coat finishes. I use either Maguires or Collinites Fleet wax. I must say the Collonites holds up extremely well on our boat hull even on the running surfaces. I think my vote is for the Collonites above all other wax products. The 303 Protectant is great stuff for UV blocking, especially on the roof material.
Once you get your kids trained to remove the stuff, send them my way and I will put them to work on our camper and the boat too