I have been wanting something like that for several years now.
I have seen the license plate mount type but here in Texas, the mount will block the state "Texas" if you keep it there all the time and you will get a fine if the police see that there, all the decorative license plate accessories cannot block the state.
I was thinking of making the camera part into a remote sytem with a battery and magnet but looks like this has done it and it looks like it might be built good to last a while.
I was hoping it would be less money than $200 but what it saves in aggravation and getting in and out of the truck to connect the trailer would be worth it to me.
I might get one in a few weeks.
Thanks for posting this.