Bed Rail Clearance?

I think you are going to be fine. You have 1 1/2" to start with, and the truck will squat 2". Towing an inch nose high isn't going to be a killer. You also have the added advantage of an air hitch if your clearance is is less than 6". Say you are backing tight up an incline and the front of the 5er wants to lean into the bed. Just get out and air up the hitch to give you an extra 2" of clearance. Just as easy as dealing with a sliding hitch.

When towing, the bouncing of the trailer and the give of the Trailer Saver will not threaten your bed rails. Maybe 3/4" of movement.