The LEDs will be installed under the bed rails in aluminum housings with flood lenses. For my use case, I want to incorporate an illuminated power button and a separate dimmer. The images above are of the box that will protect the potentiometer, PCB (printed circuit board), switch housing and wiring. I will mount it in the dead space behind the tail lamp. The face plate will attach to it from inside the bed on the post.
Agree that this is overkill and that there might be an easier way, but I'm having fun with this way – I get to use the 3D printer, the mill and my personal touch. It will be an incredibly clean, classy and durable install. More pics to follow.