Thanks for sharing.I know it is a lot of headache,but there is so much difference in the handling when towing between my old '03 4.6is and the '12 3.5D that sometimes I want to abandon that sea of torque and go back to the 4.6is.I had more than 7 k lbs hooked up to the E53 in a few occasions and it performed as there was just an empty trailer on the back.
I am thinking also about some kind of helper air springs,american style,but didnt find anything that may work.