Why doesn't the vanagon work well towing was the question. My guess is that it is too short-wheelbased.  My 2wd, I can turn a U on a regular two lane without even using much shoulder.  Amazing!  Of course, that comes from the short wheel base and the steering lock, but short tow vehicles don't control a load as well as long ones..
  I towed a 26' racecar trailer all over with lots of gross weight inside...I think I weighed once at over 18K lbs, including my 3/4 ton Diesel Ford 2504x4...Then once, I had to borrow someone's SUV to get the trailer somewhere....Scary!  A whole different ball game with a short wheelbase.
  Just my guess..
  Don Hanson