What's the cleanest way to wire a cut off switch

Actually my switch does kill the engine as well as all electrical and my battery does sit in its own box and only the positive cable is used. The switch is not on the outside as that wouldn't help should anything occur during a run or a drive. I do have the on-off plate though I do not use it.

Sorry it's not up to par for the NHRA but at least I do not have to cut a hole in it's beautiful sheet metal outside of it's trunk to appease others while still knowing how my car runs whether on the street or at the track. I guess I am just not ready to impress others as I am only into it for the money and not trophies..

who said anything about impressing others? i race slants so i know about doing thing different but having the switch outside on the rear is a safety reason not fluff.