Bed Rail Clearance?

[BurbMan]

I grabbed a quick measurement from our new 5er (2008 Heartland Big Country) and it was 59" from the bottom of the front portion of the body to the ground. That's measurement "D" in this picture.



The trailer looked like it was sitting fairly level but I had no way to check that at the time so this measurement could be off.

Now I measured from the ground to the top of the side of the bed on my 2015 Ram 3500 and I get 57 1/2", measurement "C". That's only 1-1/2" of clearance between the truck and 5er.

The trailer didn't have a pin box on it when I saw it so I don't have measurement "A". It's now got a brand new Rota Flex pin box on it. I just got a Trailer Saver air hitch, but don't have it installed yet so I don't have measurement "B" yet either.

How much clearance should I have between C and D to be sure I'm OK on inclines, bumpy roads, etc?

[Cummins12V98]

Subtract A from D. Now subtract 6" from the answer. Now place a straight edge (2x4) across top of bed side to side above at top of the hitch 5th wheel. Set top of hitch 5th wheel plate to the final dimension to bottom of straight edge and top of hitch 5th wheel plate. This will give you the 6" needed for bed clearance. B & C are irrelevant.