but can you do this with a TC?

sabconsulting, you're absolutely correct. I missed that CoG on the trailer. If you look at the photo, the 5er pin is between the rear tire and the back end of the trailer. So, all that weight of the 5er trailer most definitely makes the front of the car-carrier trailer zero weight, which will cause nothing but fish tailing on that car-trailer. Can't imagine how that would cause the 5er to track then. Yikes, the more I study this photo, the scarier it gets! Good point there!