So, a flap disk on the angle grinder got through the bed liner, and make quick work of the bondo covering the aluminum plate that was blind riveted on the bottom of the hull (starboard side). Figure I'm going to need 6-8 more disks to clear the bottom down to a nice clean bare aluminum hull.
I plan to seal up the patch, crack, and small crack in the chine up real good with some 5200, then a good coating of steelflex. Then I'll flip her over and start working on the inside, stripping paint, sealing bits and seams. Would it be worth putting some steelflex or something like gluv-it on the inside to add protection against leaking, or should the steelflex on the outside be enough do you think?