Floorboard hole leakage

[Steve L.]

I'm stripping out all the seats, belts etc. to put in new reinforcement brackets on the bottom side of the floor board. (Body is on the dolly for both rocker channel refits from a doner)

While taking these items out, I've noticed signifcant corrosion near all the fiberglass bolt holes indicating that water seaped in past the reinforcement brackets.

I'd like to add a sealant at the holes to prevent this in the future. Anyone suggest which goop besides silicon?

Thanks