I removed the rear license plate today as I am beginning an install of a Garmin rear camera.
Does anyone know what this hole is in the body?
There is a small bolt that appears to go through to the trunk but I can see know apparent use for it.
Could it be something to do with a convertible, something that I do not have.
It would make a great passage to the trunk for the camera cable.!

 

I looked at the same thing when installing my back up camera. AS far as I can tell there is no passage through the bumper molding into the trunk. The hole is to access that bolt which I think is part of the trunk latch. I opted to go under the trunks lids rubber molding and behind the plastic panel at the back of the trunk and over to the back up light. The wire for the back up light is Gray with Yellow stripe, although from the plug connector to the light they just use plain wires. I opted to pacth into the Gray and Yellow wire just before the pug connector. Good luck.

 

 

I looked in that hole after your post, i would make a guess that the metal strap or plate in there is part of the bumper to body attachment.
I may have to go your way M55 but will take another look tomorrow, thanks for your reply, i may be contacting you.