I got a set of R&G heated grips too and having the exact same problem! although mines the boxeye not fox and bars are slightly longer it seems, only overhangs by about 3mm or so, I got around this by fitting a few shims on the screw that holds the bar end, so it still tightens up fully but doesnt press against the grip. Not sure if you could do the same, might be worth a shot but 10mm is a bit more of a significant gap :P I'd be tempted to try it and threadlock the bar end screw so it doesnt wobble loose from not being fully sunk in.