look on ebay for those cameras that are "built in" to the license plate light. Those look factory. Most of them are cheap (from china, be prepared to wait a while for it to come in). Also, check to see if your HU already has "parking lines" in the image of the camera. Those side colored lines on the image when you reverse are "projected" there via the HU or the camera itself. Be sure on that or your image will be annoying.
Hope this helps