Just use fiberglass "gel' (not longstrand) gel,with fiberglass cloth.for rockers.Layer the gel on apiece of plastic lay on the cloth then gel(like a sandwich)Make sure it's an inch wider than the hole,push in place.Use smallish strips from back to front.Sand (palmsander) then finish bondo sand.prime,paint,clear.For floors put gel mix around perimeter of hole cut an old street sign to fit (thick) one way,no parking.Those fit with no cutting.Lay in place, put gel around edge to seal.Gel dries hard as steal and is waterproof,It will never rust again. Try it .