Just route one wire from the dash main junction harness back to where you need it. The wire can probably be routed thru the center console or sides somehow.
The wire to use? Well. I don't know that look on the list.
The Pink Wire should be it. Use a multimeter to test first.
Attach a 3m t-tap to it. Then connect the meter and turn the key on. You should see the juice.
Then connect a matching size 3m t-tap blade to a small gauge wire and plug into the T-Tap. Route that wire to the back.
This should only be for 5 amp or less draw if more than you'll need to setup a fused junction box.