Re: How would you paint this truck lid?
Whether it's aluminum or fiberglass, sand the gouges to feather them out with 180 grit, then 220 grit, then 400. Scuff the rest with scotch brite pads, then prime. Resand with 800-1000 and paint with a 2-part auto paint, usually urethane enamel. Clear coat afterward.
Or...slop on some house paint with a mop...whichever suits your taste.