I know I am new to this forum, but not new to towing and I felt I needed to add something to this thread.

Don't rely on the BMW's maximum towing capacity. A truck's wheelbase, weight and brakes have alot to do with it.

I have been racing for the last 12 years. I pull an enclosed 24' trailer with a Ford Diesel. The problem is stopping and swaying. Smaller wheelbase trucks are not ideal for pulling big weight, the picture of the Airstream shows nothing but how foolish someone might be. Even with level load stablizers and anti sway bars, I feel my trailer sway when the tractor trailers goes by on the Interstate. I am very smooth and deliberate while pulling, but during a rain storm a few years I slid through a red light.

All I'm saying is be careful