Well guys, much as I'd like to take credit for figuring it out for myself I can't.... Instructor at one of the fiberglass body and mold building seminars I went to a number of years back.... On the Merc's I use an industrial enamel paint with a hardener and scuff the area with 80 grit on a DA so the paint will work into the glass good. Of course when the customer wants to spend the extra $$$$ I finish the bottom with the same finish material as the rest of the body. On a driver type car, I've started using the brush on bedliner on the inner fenders. It helps with quieting down the road noise and as a bonus does an excellent job protecting from getting star cracks in the fenders when a tire throws up a rock or debris from the road and it hits the inside of the fender.....