So after looking around, I found a factory camera that is basically plug and play. The Toyota FIT (not the Honda Fit, this FIT is some Toyota acronym I think) camera system works, and I found the OEM part from a Toyota dealership on ebay. This is the same camera that's plug-n-play for the new Toyota Camry, Prius, Matrix, Venza, Tacoma, etc. Cost was about $130-140. Great for an essentially plug and play kit.
Looking at the plastic trim that holds the trunk release and licens plate lights, I noticed that there's a manual key unlock hole on the right hand side. The camera fits nearly perfectly in this hold. I also noticed that there is an INDENTATION on the exact opposite side, where the OEM backup camera is SUPPOSED to be installed (hence the offset lines on the navi screen)
The kit COMES WITH a hold drill bit that you can use to drill out the hole in the plastic trim, but I didn't have a power drill with me, so I'll have to move it over later. For the time being, out came the manual trunk release and in went the camera.
Here's where the manual trunk release went, replaced by the camera. NOTE: I didn't seal it w/ silicone since I'll be moving the camera soon, but once installed permanantly, you'll want to use some silicone sealant to keep it in place.
Inside of the trunk. manual latch is removed, and the cable is ziptied to prevent it from moving around.
Wire is run with the other wires in the trunk lid, and through the rubber pass-thought to the main cabin.
Wires tucked along driver side edge. I ran the wire down this way (no need to remove any trim, under the driver rear seat, and through the center console (sorry, not many pics here). NOTE: the 4 small wires on the camera line. One pair is for flipping the image, and the other is for removing the lines. For the BRZ, you just need to remove the lines.
Here is a pic of the plug and play harness. I would've used the ACC power from the harness, IF I had remembered which pin it was... but I forgot, so I used the ACC power from the 10-pin connector circled below. I found that a ground connection wasn't needed, as the camera worked fine w/o a ground. However, I grounded the wire to the HU anyways.
Future additions:
I'll be moving the camera to the correct (driver) side of the rear trim once I get a power drill to cut out that hole so that the lines on the navi unit match. the car. I'll also be doing the parking brake and vss disable at that time. I didn't do this today because I didn't have a switch available.