http://www.rvcams.com/p/17/70-CHNV.html
I have an older version of
this one I think. It works GREAT in all scenarios I've been able to throw at it. It simplifies passing. I can back into tight spots in the dark. I'm very happy with it. I haven't been able to use it with my new tow vehicle yet though.
If you don't buy a dedicated system, and go with something like a license plate camera, make sure it's intended for full time use. There's two basic camera technologies, CCD & CMOS. CMOS cameras can be pretty short lived if used full time versus just backing up.
Quoted from rearcamerareviews.com: "Rear view camera sensors are either CCD or CMOS. CCD sensors provide a much higher quality video then CMOS and operate in lower light environments. CCD rear view cameras are more expensive than their CMOS counterparts, but this is truly not the factor where you want to skimp on money. A CCD camera is the only unit to buy."