I have 2012 E-350 24 Nexus C. When I started towing my 6 X 10' {8' tall} cargo trailer I added Air Lift5,000# air bags. Without them the rear end would sag 1.5" with a the trailer loaded to 2,600#. With the air bags inflated to just 50# the sag vanished and the top of the ball is exactly 16" high per the trailer manufacturers instructions. When not towing I keep 25# in them and this too improves the ride and handling.
I did replace the original shocks at 33K miles with heavy duty Bilsteins and could not be more pleased with the results. Get your coach weighed as you normally travel and take those weights to your tire manufacturers load inflation tables and air your tires to those numbers.
Works for me.
:C
