People have said it's possible to install a subwoofer with the existing Bose system. I also noticed in the rear left console (over the wheel) there is a space to install a sub. How easy is this to do? Is there a wiring harness already in that space? I'm a novice audio guy, so I don't want to take on more than I can chew (ie, running wires from the HU to the back of the truck).