I drove to the storage lot today for the first hook up to my 5er and 2014 Ram 2500. I could not see the hitch over the back seat headrest. I hooked up with DW help. Found these measurements after I sat the 5er down. The truck settled from 59" to 56-3/8" (measured from top of tailgate). I had 8" clearance on the bed rails. But unfortunately the trailer was high in the front a good 11 inches. I dropped the hitch as far as possible ( 2-1/2")and will hook up again tomorrow and see what I have.
A side issue was being able to back into the pin. I may have solved that issue. I had two tennis balls on extendable rods with magnets on the bottom. When I put the tail gate down before backing I stand these rods up , one on end of tail gate and one just inside the box, both centered. As I back up into the pin I keep the balls in line with the pin and as the pin passes over it knocks them over and I hit the pin dead on. I will see if it works that good tomorrow.