Thanks!
I took the Velcro off and cleaned all the glue, then roughed up both sides with some sandpaper.
I applied a good amount of epoxy to the back half, stuck it in place with some clamps and let it cure.
I then went in the back and hot glued the heck out of it just to be safe. The seam isn't perfect, but I'm afraid bondo will just come right off so I'm gonna live with it being messy.
Superglue didn't really want to stick, but the epoxy seems to have done the trick. Good luck!
Could you please post some photos of your helmet? Im really interested in what your adding to it