[wingnut60]

4happyfeet,
I don't have the risers, but do have a '17 450--my B&W hitch is at mid-height and have fair clearance--I did cut the flanges off the pin box outer plates as that is the part that contacts the bed rails, if any contact is going to happen. Just be careful after hitching up and make a few sharp turns, both forward and backward, while keeping a close eye on the pin box to bed rail clearances. Doing this will confirm any potential problem. Suggest that you do this AT THE DEALERSHIP when picking up the trailer.
I am almost level in stance when hitched, no air bags, maybe 1" high in front. I even have a Retrax bed cover on top of the rails with just small dents in the rails before I cut the flanges.
Just this Sept at Morryde, I was quoted $2200 to install the rails.