We have a flat V dip in our driveway, and it used to rub the bottom of the spare tire, especially loaded. The low clearance made me crazy, so I had the axle "flipped" (from the factory the leaf springs were hung under the axle with U bolts; now the leaf springs sit on top of the axle with U bolts.) That got me an extra 4" clearance. You might want to check out the axle orientation on your new rig; maybe the dealer would flip it? ($100 project).
Also I went from 13" wheels to 14" LT tires... another 1/2 inch.