Subispeed order arrived today. Broke out the panel clip tool set and started working on it. I needed to remove the upper panel that covers the rear view mirror camera and the driver side down panel on rear window. I took the screw pin out on liftgate lower panel at lower left corner of window, reached in and popped the first push clip on liftgate panel. Popped the small panel where the light fits in. Poked a fish tape thru a long narrow hole I could see from corner by window and it came out the panel hole. Hooked the light wire on fish tape and pulled it thru. plugged in LED light and snapped it in to position on liftgate. Ran wire up along side of existing harness and taped when needed.
Second wire with the bigger connectors, was a bit more of a challenge. Removed the interior panel at rear of ceiling, 4 white push pin clips. Needed something flexible I could feed through the rubber grommets and tubing from liftgate to body (drivers side) a piece of THHN 12ga wire was perfect and I fed it thru from body to door. Taped the white and red wire from provided harness and pulled them through. Pushed the ends into the connector and taped it to wire from LED light.
Next was lower interior panel where exiting cargo light and Cig lighter is. Remove 2 screws, one inside the cargo net hook and the other just above that behind a little round plug cover. Loosen the upper panel, one clip to reach inside and pop with tool. Then lower panel has 1 clip that needs to come out also. Pop the cargo light out and unplug the connector. You will be able to reach between the panel and body and view the seatbelt retractor for drivers side 3rd row. Route the cable down and around the pin you popped out and it will not get in the way of seat belt. Reach further down and you will find gray harness that is wire from cargo light pull it out and plug it into the big connector on LED light harness. The LED may light now, depends on how long you've had the rear liftgate open. Other connector will get poked back through the hole in panel where the cargo light mounts and plugs into cargo light. If you routed the wire correctly and didn't leave extra slack somewhere you should be able to just pull the inline fuse through the cargo light hole (so if it blows sometime you won't have to take all the panels off to change it). Tested it all out and works great.
I put things back together testing as I went. Time spent was a little over 2 hours from start to finish, but I'm confident it could be done in well under an hour if I had to do it again. I spent quite a bit of the time sorting out how to take it apart.
Really happy with the outcome, now I'm ordering the LEDs for other lights.