I have a 2011 ES with the factory radio unit installed. I know that some of the higher trim models come with the navigation and backup camera options and I was wondering if it's possible to upgrade to one of those in mine. I've found used units with the nav/monitor built in, and finding a backup camera to work with it wouldn't be too difficult, but I want to know if it would be as easy as plug and play or if there are additional wire harnesses/accessories due to the navigation. Has anyone else attempted this swap? Any and all comments are appreciated!