Power wire of battery with a fuse. 2 gauge or 0 to be sure. Run into a fused distribution box up the back of the car from 0 to 4 gauge.. Common ground is fine (as in sharing the same bolt hole to the body of the car. Common remote wire is also fine as it's low amp and low voltage. Done. Don't need a capacitor.
You could probably do it with 4 gauge then split into 8 gauge but I wouldn't trust it.
Think its funny that the title is called for Shits and gigz. I wasn't drunk, just trying to do a rough mock up to show a mate, yes I suck at paint lol but it's a basic draw up that helped him understand, I wish I was on something but sadly enough I was only on lack of sleep lol