I started considering this as well. Most of the tracks I want to go to are ~350 miles away; I have no interest in racking up miles on my M3 driving to the track. And I might use the setup for a dedicated track car later on, and the X5 for the winters. I'll have to find a place to store the trailer, but I guess I can find a lot in the suburbs or something.
I've been looking at trailers and I found one at 2000lbs, so the total is about 5500lbs. The X5 is rated at 6000lbs, so that should be fine. I trust the rating methodology.
I don't have an X5 yet. Boy, these things are selling for 12k-13k with ~80k miles. They have taken a hit clearly. I would rather get the 3 liter version. Is that also rated at 6000lbs? Is the rating for the chassis, the power, or both?
I see that it would cost about 1k to get the dealer to install the hitch. Any suggestions on that?
Also, are the brakes on the trailer a requirement or a recommendation? I can see things getting really tight if you were to rely on the X5 brakes only with a combined 10000lb and a pivoting mass in the back. Should I be looking for a specific type of brake setup on the trailer? Are there any issues with making the trailer brakes work with the X5? How is the brake bias controlled?
Finally, are there any insurance concerns here? If both cars are on my regular policy, will they both be covered in a tow situation?
Thanks in advance.