use the dremel tool to cut a straight slot in the center, and use a hand impact driver with a tip that fits the slot well, i guarantee it will come right out with less than 5 minutes work. i have removed a hundred bolts and such with this technique and don't even bother to try any other method. just my two cents, but i tear down bikes for a living and have had a lot of stripped stuff over the years. if it is really tight, torch the motor case for about 30 seconds, keeping the torch moving. it will make the metal expand and aid with removal. a propane torch is all you need, or a heat gun would even work.
2003 VN1500 Nomad FI Bagger
2004 KLX400SR Dual Sport light adv bike
1969 CB750 K0 sand cast #1767
couple of nice GL650 Silver Wing Interstates, one with hack
2 and 4 stroke dirt bikes
other vintage stuff back in the corner