Thanks to @wk057 sharing the information on a spare switched circuit (Spare Switched 12V Circuit on Model S built after July 2014) and I used that information to add a 12v socket to the back of the center console. I had already added the integrated center console with the rear cup holders, but it is lacking the USB ports that the facelift cars have. I know this isn't the first time this has been done, but I'll share a summary of how I ended up getting this to work on our car. Parts used: Tesla 12v accessory socket (part #1011678-00-A) A whopping $4.00 at the service center. Ford pigtail connector for connecting to spare 12v Misc. wire and connectors for running power from 12v source at front of console Step 1: Disassemble the center console. I found a good reference online for the installation steps on the integrated console, so I used those instructions to remove the right side trim, rear vents and rear panel from the console. Tip: removing the right side requires removing the rear panel first, so start with the vents, remove the rear panel and then finish with the side panel. Reinstall the parts with the rear panel first, then the side panel and finish with the vents. All of the parts are held in place with "Christmas tree" connectors that pull off. Step 2: Tap the spare 12v switched power source using a spare wire from a Ford pigtail connector. The Ford 1.5mm pins fit the Tesla connector. See YouTube videos on replacing pins in automotive connectors for instructions on removing and inserting wires. There is a useful catalog of Ford connectors at https://www.fordparts.com/FileUploads/CMSFiles/18376%20Pigtail%20Book%202016.pdf and the matching connector for the connector detailed in the other forum post is the WPT-1260. I couldn't find that exact part available anywhere locally, so I just used another connector that had 1.5mm female pins. Step 3: Installation. The gentlemen at Walnut Creek Customs in Walnut Creek, Ca. took care of drilling the hole in the console's rear panel for the new Tesla 12v outlet and they also built the wiring harness to run power from the pigtail on the spare 12v connector to the rear seat. I left the soldering and crimping to people who are a lot better at automotive electrics than I am, and they delivered great results. Thanks Walnut Creek Customs! Step 4: Run the 12v wire along the side of the center console to the rear panel and connect to the new 12v outlet. Install the rear panel on the console and then install the right side panel keeping the wire in the channel along the side. This was probably the slowest part of the job due to tight spaces between the console and the passenger seat. Finish with re-installing the vents at the rear of the console. Step 5: Start using a 12v outlet in the rear seat! Peace and harmony for the kids on road trips. I mounted the new outlet on the underside of the read panel due to the space that was available on the panel. There appeared to be enough space on the panel between the air vents and the cup holders, but that space looked like it would be limited for space if the cup holders were in use, so I chose to use the lower location. Not the most convenient for plugging things in, but considering how rarely we end up actually plugging and unplugging devices from the charger I don't think it will be a hassle. Using the factory part gave it a OEM look on the install. Pictures: Extra wire (red/green) installed on the Tesla connector in the position to connect to the spare 12v switched power source. Donor connector for female pin and pigtail (the red/green wire has already been removed from the top/right corner). Wire harness built by Walnut Creek Customs running along right side of console. Before the console was re-assembled, the harness was run along the side of the console into a recess that was a perfect size for the harness. Harness at the rear of the console waiting for connection to the outlet. Rear panel exterior and interior shot of 12v outlet. Finished installation.