Started the dash.
First, I V grooved the cracks.

I was concerned with the fiberglass Bondo reacting (eating up) the foam, so I decided to see if there was anything left in this can of great stuff. (I kept it around for target practice)
The propellant was long gone, but the resin in the can started foaming up when I stirred it, then I dabbed it into the grooves. When it dried, I trimmed it down with a razor blade. It was a bit porous, so I smeared some glazing putty over top, waiting for that to dry.