I didn't see it mentioned, but will you be running some USB cables from the Mac back up front?
I have one that comes up to a 7 port hub under the dash, where I have the wireless keyboard, OBDII, Andrea USB mic., GPS, touch screen, and two more ports run for charging devices. One to the glove box, and one to the center console area. (Bluetooth is in the trunk, so I can remove/replug it as needed for testing, since it's such a pain to get working.)
I also ran an 5v power cable from the P2140 to the hub, so it had full power available.
On top of the above, I have also run a shielded audio cable to the factory radio, HDMI to the touch-screen, and a cat5e that carries push button and LED signals from the computer.
I've opened up the center pathway though my car 8-10 times already, so wanted to make sure you'd thought of all the above items already.
Nice job on the interior btw-