Seems like that would be difficult to prove unless they caught you turning it on.
Ah yes but they have found something for that....Having the switch alone is illegal...
So if you get pulled over and they stumble on it...you are screwed and every year they check your car and you have to hide it very good or they will find it.
This makes all sorts of cool stuff impossible to have:
Big front lights switchable on from inside,any under the car lightning, big car horns, etc...
Yep..living in the USA is a blessing for car lovers...
BTW: I'd mount the back lights on the rear bumper; out of the way of any rocks you might crawl or mud you might cross.