Another thought with using a dremel to make a straight cut on the head is to use the tools made for brake rotor screw removal. It has a couple of bits, one being a flathead. It's the one where you put the tip in, I know haha, and hammer on the other end to loosen whatever you are trying to get off. I used mine once as intended on an 08 CRV and have used it many times on bolts that I have stripped the head on.