you could always just get a splitter
for one side for your cell and gps, then get one of these
to run to the back, since it's just a "just in case" deal. I have the 3 way one...used it in my Durango and the wifes Magnum back in the day, it comes in handy with my ST and her Charger. I'm actually going to hard wire one in the bed, I have a 12v impact gun with a medium length cord so it'll work out nicely with one mounted near the tailgate.