I am not a fan of rtv for marine sealing or bedding, I just don't trust it. I would consider it to be of great importance to possitively seal the holes. If the holes are not properly sealed,and water penetrates, the fiberglass could delaminate from the foam, bad thing! 5200 would probably do the job, I don't believe it to be a quality repair. good luck
_________________________
"The best argument against democracy is a five-minute conversation with the average voter."
Winston Churchill

"So it goes." Kurt Vonnegut jr.