Truck bed rail to 5th wheel clearance recommendations?

[vipermanden]

I have a 2016 RAM 3500 4 X 4 dually with the auto air bag leveling, and the Companion 25k hitch I have, is on the lowest setting, and it still seems that my 5th wheel is tail low. So I told the dealer to raise my pin box to the highest set of holes to see if i finally get level, but then I'm wondering if my bed rail to bottom of 5th wheel clearance will be too little? I can't measure it right now, because it is at the dealer being worked on. So do you take the 5th wheel hitch, and rock it back and forth and measure the angle and transfer that travel out to the width of the trailer and if the number is less than your level clearance you are good? Or is there some other number you all shoot for to be above the minimum clearance?