I have the full bumper hoop, giving me different options. The backup lights I'm using originally housed MR16 halogen bulbs, but I swapped those out for LED arrays from a couple of low cost flashlights. Flashlights, of course, run on a lot less than 12 volts, so I gutted a cheap USB car charger, mounted that in a small plastic pill bottle and wired it in to provide 5 volts to the backup lights. The flashlights and the USB charger came from a local dollar store.
This is driven by a micro-switch mounted to my Richmond 5 Speed Street transmission which, of course, has no internal backup light switch. The micro-switch is actuated by the 5th/Reverse shift arm.
The lamps are mounted to the bumper hoop using rubber-insulated Adel clamps.
Purists may cringe, but I had to satisfy the regulatory authorities to get it approved for street use. Ditto on the reflectors mounted on the bumperettes / over-riders. Both still better than hacking into the body.
Photo:
https://www.amazon.ca/photos/share/n...RoIjy39rCPlG5b
Note: I looked at the license plate mounted centre stop lamp, but regulations here require a minimum height of 860mm, or just under 34".