try a 1m long breaker bar (laser do them),
it should be about the tension that it takes to break the head off (if its a chromium 1/2" bar)
if its hardend black head you should be ok(just) though i'd expect the end of the bar to be pretty unhappy about that much stress on it...
(im doing the same at the moment as well)
the nut is 36mm, you should really use a single HEX socket, a bi-hex is likely to cut steps in the nut or worst case round it off!
the torque loading is pretty much into 3/4" to 1" socket loading sizes (thats truck repair tools (with a short scaffold pole on the end to increase torque when aproaching 300NM or over) to the non-mechanics out there
The last time i saw someone trying to get wheel nuts off a Coach was on the Pan-American Highway at 2am after mowing down a stupid bull that had wandered into the middle of the road. It took 4 guys jumping up and down on a 4m scaffold pole to undo them, and they had to blag 4 spare wheels off passing coaches. (dunno what they did about the half tonn of beef left on the side of the highway, someone had a steak or two the next day.)
anyone know how to get the steel caliper spring off, as mine is seized in the end holes ???
i've tried bending it, but it wont come out, my only option is to snap it off....