Controling Power To The Cigarette Lighter?
If you are only using a GPS and phone charger what ever wire size the cig lighter has will be good, neither draws a lot of amps.
Just a thought... why not start at the cig lighter. I believe there is a single post on the back side, disconnect it and make a mating plug to attach your (I assume) dual cig lighter adaptor
Forgot to mention mymopar.com has free wiring diagrams and FSM