Adding this was too easy. A couple of holes in the headliner, 2 wires, one mounting screw, and a ground screw. Now there's room for glasses and more. I've since traded the garage remote door for a HomeLink module. I've also swapped the dome lamp to one with swivelling map lights. For more info, click this:
There are no wrinkles in the headliner - those are just reflections off the car parked next to the truck.