I'd do a more thorough repair and use regular glass mat and resin in that case. I don't like leaving fasteners underneath such repairs, instead I would glue and then fiberglass the wood to the inside like is done on many brands of trailers, like Escape.

Hi Thrifty Bill, I have a question if you are not too swamped. I took the belly band off my 75 Ventura. There are screws above the seam all the way around, some are not catching on to anything. Should I remove them all before I put on filler? There is a little bit of give in the top part and bottom part in some areas right above and below the seam line when I push down, almost like I need a screw to secure them tightly. And it looks like I have a little bit of fibreglass repair work on the corners, the gap is probably close to a half inch, would you recommend reinforced fibreglass filler for a gap that large? Thanks for any advice, you seem to be an expert. Sonny