Clearance Between Bed Rails and Fiver. Yikes!

Well Rick, at one time, somewhere in here, I think I told how high it was from ground to top of my tailgate, but it excapes me down and at 23 degrees and snowing....I'll check later. When I dropped my 5er into the bed of my 13' in Novemeber, it dropped about 2"....The picture frame adapter is taller than regular rails, so I dropped the height of my Reese 20K Signature hitch one notch...I have a "tad" over 5" of clearance between bedrail and bottom of 5er that could contact bedrails. I pulled the 5er off my property in WV, made a sharp right turn up a short steep hill, leveled off and had a little over an inch clearance from hitting 5er with bed rail...I back up a semi steep driveway, and truck will still be heading downhill while 5er is leveling off and still no contact, and reality, the 5er is setting "more level" with the 13 than the 12 or the 10...