do you have a 1/2" air gun that you could put on the socket and let it rip....it will come off that way! you may need to spin it until it heats up a bit and/or wears out the lug or socket so there is more slop, but if you spin it enoguh with a gun it will come off.
could you get a torch in there without damaging your rim? a little heat goes a long way!
also....if you have access to liquid nitrogen, or even propane (no smoking!!!) you could freeze the socket, it will shrink and possibly grab the nut hard enough to spin it off.