I had a jackass inspector that insisted I have TWO backup lamps. I did install an older Mini-Cooper backup lamp under the trunk latch.
Got two trailer style units, some scrap aluminum and hooked them both up to my tranny switch:
Afterwards, I removed them and have been running around with just the one Mini-Cooper lamp.
BTW: I have two trailer lamps with brackets if anyone wants them to pass inspection!!!! PM me if you really want them.