Jst dont use fiberglass and resin ive seen plenty of ramps repaired this way and the fiberglass has let loose
i use either acrylic welding adheasive goto the hardwar store and get a good universal plumbing adheasive and primer this will weld the plastics together let dry 1-2 hours then cut a reinforcing piece of abs scuff both sides with 120 grit sandpaper and use the welding adhesive to add a reinforcing plate.