I've got one camera in my grill and one on the passenger mirror. They are tied into my head unit...
I initially thought this would be the best things since sliced bread for rock crawling.. and it is slightly useful, but the problem is that it's really hard to get depth perception via a camera and a display. Maybe some better quality image processing could do the trick, but overall I find it to help on occasion, but nothing beats getting out and looking..... Part of the problem may be the wide angle lens (but that is what you need). I've thought about trying to buy/build some type of video stitching solution that could combine multiple feeds and get rid of the wide angle lens and do multiple cameras...
Works perfect for parking... since you are not trying to differentiate the height of rocks... It's amazing how they all look exactly the same on the screen. The view of the passenger tire from the mirror tire is pretty useful though. Allows me to to see where that tire is in relation to the terrain. Just hard to tell exactly how tall.. the terrain is.