Have you seen the thread below…lots of hitch info -
http://www.xbimmers.com/forums/showt...ighlight=hitch
From the thread above it looks like forum member 'gan23' has the OEM hitch on his/her X5M. Yes, the OEM setup requires your rear bumper/diffuser to be cut, as pictured below -
I went with Execuhitch on my E70 M Sport - no cutting required and no visible hitch receiver unless you're towing. They make a hitch for the E70 X5M as well (link is below). Do you live in the Seattle area (WA plates on that X5M)? If yes, I had a local body shop which specializes in BMW's install mine. Many do it themselves but I didn't want to bother with it.
http://execuhitch.com/tow-hitches/bmw-x5-and-x5m/