Ah yes, I've had that problem. I couldn't even get a socket in there. I ended up sticking a 5/16 wrench on there and welding a bead across it. Had to chisel the weld once I got the bolt loose, though. I don't believe the bolts had a shoulder or step, so you might be able to just dremel the head off.
It sucks having so little room, and the only thing that fits is a tiny little box wrench. I had even worse luck on these same bolts on a Nissan Frontier. They used some serious locktite on those! It took a 4-ft cheater bar long enough to stick out from the vehicle so I could jump up and down on it. Turned out the u-joint in the shaft was never greased at the factory.