I use an invisihitch for pulling my boat. If I were pulling an RV with an X5 I'd say screw BMW and their "we want our cars to represent performance and not towing" attitude. I'd still have some type of anti sway bar device or weight distribution system installed. And I wouldn't exceed the recommending towing speed with an RV.
Check this article posted today:
http://www.dailymail.co.uk/news/arti...l-crashes.html