My first van - rear view camera question

Hi all, I have just picked up a 2006 Vito 111 van - it is the one with panelling all the way around. I have a question about rear view cameras... does anyone have one fitted? If so can you offer any advice... I think I want a CCD camera that has a monitor fixed where the rear view mirror would be on a car and with a camera either mounted in the bumper or on the top of the van... the camera mounted in the bumper sounds like it would be less prone to vandalism, but I wonder if I would get the required view I needed. I have some tricky reversing to do, out of a parking bay on a main road where the parking bays are at an angle to the road..

Any advice much appreciated as I'd like to get the correct camera - I also want the camera to be always on to serve as a rear view mirror whilst I am driving so I know if anything is in my blind spot when joining motorway or changing lanes etc..

Thank you in advance,
Clare.