Andrew this is a great light. I installed mine today, I clipped the alligator clamps off and fed the wire through the vent hole just left of center where it is to be mounted, then out the next hole towards the window. From there I taped it to a thick piece of weed trimmer string (didn't want to risk the coat hanger poking through something) and fed it down the c-pillar to behind where the rear arm rest attaches (I removed the rear seat and arm rest for access):
Then I centered the light in order to adjust the slack but didn't stick it yet. Then I pressed the wire between the headliner and the black piece of vinyl (I later straightened it so you can't even see this):
Next I fed the wire into the trunk and hid it behind the left piece of wheel well grey plastic, then behind the side elephant skin, then back to the rear light housing. I tapped the red into the brake light connection and grounded the black to the housing.
Then I centered the light, took off the adhesive, and stuck it to the upper slanted piece of roof, up into and behind the lip of the headliner. TOTALLY invisible when looking from behind, but lights up nicely when on!
If you are thinking of a 3rd light (yes I was hesitant also) this is a great piece. Thanks for making these Andrew!