Now I have some more information. I got a message from Brink (
Thule Towing Systems ) that manufactures towing hitches for BMW also, the sales rep stated that there are actually differences in body of the car and therefore Euro hitch will not fit to US spec X5.
Also local BMW dealer could not find out if the Euro hitch could be installed to my car or not.
I've asked confirmation from BMW Country Importer and Westfalia hitch manufacturer, I'll wait their responses also.
I know that Euro hitch receivers can be detached and cover plate used to hide the hitch and according to Weasel's comment same applies to US spec hitch.
Anyway, if the Euro hitch turns out to be impossible to install then only option would be to order US spec OEM hitch, let's see.