It depends on how "bad" the fiberglass is... do not leave as-is. That stuff will get in your hair and itch like made, or it can get in your eyes (trust me, had it happen)
My advice would be to sand the fiber glass down by hand. I'd than use an aircompressor to blow it off real good and coat of something like "PLasti-dip" (you can buy it at home depot), the rubber stuff you dip tool handles in.