BMW Towing ?

[Chip]

I have the 4.4 05 X5 w/the OEM hitch. I have to help a friend by towing their stuff for about 250 miles. He has a Uhaul 6'x12' trailer and we can attach it. Now, with the steptronic, do I have to do anything special, so I don't hurt tranny/engine? Can I drive it in the Sports mode? He has a lot of stuff and will weigh around 4,200 pounds. Also, I have to make another trip towing his trailer (he has another car, so hell drive that back). It is pretty big, around 3 tons. Will I be able to tow this at speeds exceding 80? WIll the back break off or something if I am too fast?

You may think, wtf?, why are you doing this, but he has helped me a lot before when I didn't have much help... So, yea...