RE: seamaster modification advise please
Using coverite and spray paint has worked for me, taxiing back to a silt/sandy beach with just enough speed to get the nose within reach. Finish shows light scuffing, certainly nothing that would leak water. In reality the plane is not in the water all that long, taxi out to takeoff and taxi back to return. Believe fiberglass is a lot work and weight with little benifit, unless of course you plan on flying off of rocks all bets are off.
Can't say I have had much luck trying get monokote to stick to polyurethane, did do poly inside the main compartments, just in case, sealing the wing saddle with silicone, the inside of my plane has stayed dry.