We have the same F350 DRW Longbed towing a Pinnacle using a Curt A25 hitch. The RV dealer set us up with the hitch at the 2nd highest of 4 possible heights.
I wasn't happy with the RV/ truck clearance and raised the hitch to the last and highest bolt-hole setting. I now have my 6+ " clearance and both truck rails and Pinnacle are dead level. No other accessories, just dumb luck.