I use to have a cheap Gator branded reversing camera (mirror clip on style), that had a forward camera too, mounted to the numberplate. Had to activate it via a cheap little push button switch. It crapped out after a while, but damn if that thing wasn't handy when parking, doing 3 point turns in tight spots, and watching ruts & rocks down low out on the tracks.
Front camera failed after a while, and I ripped out the whole system when I upgraded my factory stereo to a Kenwood unit with reverse camera. Some more expensive Kenwood head units (and other brands I assume) have a front camera specific input, but not mine. BUT, it does have an AV input, if you want to run a tv tuner, dvd player, etc into the display with audio if you want.
So to rig up a front camera again, displaying on the head unit, I first sourced a front oriented camera from ebay & mounted it under the numberplate. It has to be front specific, because the display is not mirrored like a reverse camera. If you use a reverse camera on the front, the left will be on the right, and vice versa. Here's an example. http://www.ebay.com.au/itm/Vehicle-not-mirror-image-Car-Front-Side-View-Forward-HD-Parking-Camera-/261791908735?hash=item3cf403837f:g:TdgAAOSw1vlUvTWF
One thing I would advise is buying a camera without the parking space line overlay. Slightly annoying but might be helpful if you need to guage distance. I prefer it without.
They come with a 12v wire, and a video out wire (RCA connector). I ran the RCA into the cabin & into the AV1 input on my headunit, and obvioulsy connected power off the battery. The camera is powered 24/7 but uses bugger all power and shouldn't affect its longevity, but they're so cheap who cares. To pick up the feed I simply switch my stereo to AV1 input, and BOOM, theres your camera feed.
Even better, I mounted my numberplate on one of those adjustable number plate brackets, so I can easily adjust the camera angle as required. I can even push it back so I''m looking under the front of the vehicle at the wheels for perfect wheel placement on tracks.
So other than the Kenwood headunit, it cost me about $15 for the camera and $40 for the numberplate bracket. Good little mod that didn't take much time or cost a bomb.