I'm just diving in to wiring up camper shell lights and adding additional reverse lights (camper shell, under bumper). This seems consistently standard for the 7-pin.
Getting your 7 pin trailer wiring right is the most important aspect of connecting a trailer to your vehicle, besides properly physically connecting the trailer itself. This guide will help ensure you get this right so that all your tail lights, brake lights, turn signals, batteries and other...
offroadofficial.com
Just ordered this splitter for what it's worth to avoid having cutting into the OEM wiring harness.
Let me know what you come up with or if I'm headed down the wrong path.