You guys crack me up... IIRC "Bondo" is vinylester that has some fillers in it that makes it more workable/shapeable. If you added chopped glass to it it would probably be equivalent to the strand-mat layers of your hull as most hulls are vinylester resin. I still prefer the
epoxy with fillers; easy to mix/use and has better adhesion properties.
You can avoid lots of prep work (and lead dust exposure) by not removing the existing
paint from the keel; that was why I mentioned not sanding off all the existing
paint.