Well everything finally got done today aside from one huge issue. The JL 12" sub magnet is too big for the custom truck box that I got. FML. I was told a very specific shallow sub would work (Kicker CVT 12) so I have just ordered two of those and will be returning the JL's.
The screen is all done with all steering wheel controls working properly. My CCD Rear Cam kit that worked with the oem gm nav screen and gmx-550 lockpick actually works with the Pioneer screen so I'll be returning the Pioner ND-BC6 rear cam I just bought (which I'm happy about because the CCD rear cam is drilled into my tailgate handle whereas a Pioneer aftermarket cam is in the bulky square housing that has to be mounted and screwed down). The amp kit is ran with the JL amp going underneath my driver side second row bench seat and speaker wire ran to the box.
It's nice being able to use my phone for bluetooth audio WITH all the ID Tags showing up:
Main phone menu:
Will take more pics of the amp and screen when it's daytime tomorrow.
The Kicker CVT 12 Shallow mount subs I just ordered:
http://www.kicker.com/comp_vt