Originally Posted by JCL

Glad it is working for you.

Have you calculated the bending moment being applied to the hitch? When BMW publish 600 lbs tongue weight limit they specify that the maximum load distance is 8" from the pin. Your CoG would appear to be a multiple of that, hard to tell from the pictures. Not sure what your hitch manufacturer publishes as a load limit for carriers, but it shouldn't be the same as a tongue load limit.

Also, BMW publishes a lower limit for bouncing loads, 330 lbs tongue weight. They use the lower figure for non-highway, where a load isn't always constant.