I have been using 160 rotors at the back, had no issues with clearance yet, but i have been running them slammed all the way back. These rotors are some generic avids, that came with china bb7's.
But i have the same issue as you, on a different bike, just on the front, i just added a few washers until it stopped rubbing, tightened the caliper bolts more than usual, seems to work fine. Im a master of dodgy setups. Hope thats helps.