My 2500 159 wb van travels daily 1/3 of a mile on a gravel road with potholes. When I go over the potholes the rear end thumps and the ride is jarring. Van is a campervan with only 400 added pounds. Dealer says it is hitting the bumpstops which is making the sound and creating the jarring ride.looking at using airbags or solid neoprene springs like Sumosprings solo to eridicate the pothole issue. Any thoughts?