Reverse light wire for backup camera?

I've been doing some searching on the board but haven't found anything conclusive on the topic. Does anyone know a good source in dashboard for a +12V signal to the reverse lights? I'm in the process of converting my 2010 from the stock JVC single-din stereo, to a new double-din unit and it needs a signal to know when to display the backup camera.

I had seen posts from a few people that they had found one, but no explanation as to where they found it.

Any clues would be appreciated. Thanks!