Ok. I came across this info this past week after picking up a 2020 2500HD Denali with 15kmiles. An upgrade from my 2003 2500HD Denali @225k miles.
Wow, the tech in this thing is amazing. So right away I noticed the bed 7 way/4way plug and the bumper and the 7 way and (what I figured out later) camera plugs were in the wrong freaking places for 5th wheel pulling.
So research lead me to here. Because, while I bought a truck for more than my first house, I still value...value in DIY. I will do the bumper to bed swap plug and have the extension cords. Near as I can tell, light blue is the 'universal' plug, so seems to work for both the factory ends to get things up to the bed location. I appreciate who put in the effort for the 3d printer files for enclosure. I have done some 'bumper' testing to confirm the light blue and the amazon camera works. Now to invest in the cable to get from back of of the camper to the plug or make my own.