I really don't have any significant additional information, but feel free to ask any questions here.
The best resource is the factory service manual, which you can download here:
https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
Essentially, you are trying to duplicate the wiring that Chrysler would have installed in the factory. There is a section full of wiring diagrams. You're looking for the sections on the rear wiper/washer and the heated back light.
The hardest part was probably adding pins to existing wiring harnesses. I tore apart some junkyard harnesses to get usable pins, and just reused those.
It does take a while to install, as you'll need to take off a good amount of dash trim and pull the instrument cluster, as well as run wiring to the engine bay.