I responded to the OP on this, and I see he is also running the adapter with the fifth wheel closer to the cab, same as I am. If wanted he could run that 8 " further back. Without checking I thought with this new fifth wheel it looked like the pin box was a little too close to the tailgate , so I reversed the adapter putting the fifth wheel closer to the cab. Still I have no clearance issues with the cab. My previous fifth wheel with the Morryde pin box I ran the adapter putting the fifth wheel further from the cab.
I started with the adapter in the forward position, pin box further back, since every one I had seen was done that way. I was not comfortable with the pin box to tailgate clearance so it was simple to reverse the adapter, moving the box forward in the bed. Had I followed the Andersen install instructions (measurements), I would have done it that way to start with. No dents... Yet!