Just curious, what kind/size of boat are you towing?My experience is with factory setup: 1) the hitch wiring is not "US" - see posts above; 2) the extension needed to clear the bumper (I use a 12") creates extra flex. I found if you use the 8" extension you don't have much room.
The first RR had the hitch but no trailer wiring kit (adding the kit was easy (BUT the wiring was not "US").
The third issue is the extension brings the ball out an angle. The boat shop told me that the tongue and ball need to be level (not dropped or elevated). This ensures that you don't drag on the ramp or dip.
All said and done the RR has zero problems pulling the boat even on the steepest grades/ramps. Remember RR has a short wheelbase (compared to the F-350 on the ramp next to you). Tiny adjustments have big reactions on the trailer.