If its just reducing foam rash and dings Polycrylic like Minwax is very easy to brush on. I light especially if sprayed or brushed on in thin coats.
Its not structural though. For that fine fibre glass and epoxy thinned with isopropanol. The isopropanol evapourates as it sets. Then lots of sanding. Then repaint.
My experience had been start looking into composite/fibre bodies.