Yes there is a gash in the metal that was hiding under the bondo.
The entire ring around the headlight bucket was bondo.
I decided to stick with what I am comfortable with. Loren suggested a propane torch but never used one, so stuck to chipping the bondo off. Thickness of the bondo ranged from just 1mm to over a centimeter in thickness. Pretty ugly. Also found two large holes still in the metal under that thick coating. And I still have large areas to chip away.