Score one for power tools. The Blaster didn't do a lot to loosen it, and already having a larger enough metal drill bit on hand, I just drilled out the top of the bolt head. As Prowler (thanks!) said above in #7-- it was remarkably easy. Once I hit the bottom of the head, the stem just popped right out and I pulled out the remaining part of the bolt. Thanks to you all for the great advice.