my custom limited did not come with the reverse camera, I have been looking at the kits available, I cam across a patch lead so you can use the existing 4" radio display screen and use your own choice of reverse camera, I have only seen it on US web sites, they are plug and play some versions need programming and some auto program, these ae not "y" boxes that cut an existing video source and put in the camera.
cant find anything in the UK
here is one of the videos
https://www.bing.com/videos/search?view ... eZwPosaPQQ