The trick to using POR15 and fiberglass is to lay down a thick layer of POR15, let dry until tacky, lay the mesh across the hole, apply another layer of POR15. Let dry until tacky, lay another piece of fiberglass mesh at an opposing angle and let cure. Smooth in a thin layer of the POR15 putty, embed another layer of fiberglass mesh, let dry and sand smooth. Finish off with a coat of POR15 or any good primer and top coat.

If you take your time and are skimpy with the POR15 you'll never even notice the repair.

You will go through a stack of latex gloves and disposable brushes but what the heck! Much cheaper than skin replacement and a pint of the POR15 thinner/cleaner.