Just used one of these to power my rear view mirror camera. Was easy to run the wire from glove box to fuse box. Attaching photo rather than link so people can find similar contraptions once the Amazon link is dead.
I was trying to find a high-quality rear view camera and this one promised to be a Sony unit. I can't complain. It does the job. I didn't know if I would like the rear view camera mirror thing but, well, I do. My backup plan was to do some creative wiring to run the camera to my Sony AX1000 head unit.
No photo of the wiring at hand, sorry, but it would be pretty boring! Imagine that red wire/cigarette adapter from the previous page laying at the bottom of my glove box. Comes in one end and goes out of the other. I ran it from fuse box through empty space where the sub would go if I had one basically at random as it was like 100 degrees out and I was baking alive while doing it. There is lots of space there to play with.