I have a 1997 2WD Chevy Astro van that I recently installed a trailer hitch to tow a light (2,000 lbs) pop-up camping trailer. I would like to raise the rear of the van a few inches to increase the clearance from the road than its current approx. 5 1/2 inches. What is the most cost effective way of raising the rear of this type van a couple of inches to add more clearance between the road and bottom of the trailer hitch?