Thanks for the info guys. Finally got to the right person at a dealership. He let me know that even though the wiring is all correct and all the hardware is installed in the factory, they leave the controller out of the dash and the programming out of the computer. He let me know that I'll have to bring it in for a reflash and that it'd be $110 to hook it up and connect to whatever server it needs to get the new programming from- he said who, I can't remember- I guess GM's programming is open source and people buy licenses, blah blah blah.
So for now I'm grabbing an old voyager and hooking it up for this trip. When I get the time to leave my truck at the dealer, I'll have them reflash it and let you know how it works
What confused the snot out of me on the entire thing, is that the wiring harness is already clipped to the back of the panel that you remove... it looks plug and play. I'm a newbie at all of this, but hopefully this is the last time I make this mistake haha.