Rearview camera and monitor to aid ext. mirror

My towcar is an MPV, and the rake of the n/s mirror demands acute neck-swivelling, and it is difficult for passenger to avoid obstructing driver's view in mirror, particularly when map reading.

I am looking to fit a small camera to the n/s extension mirror, with a monitor to left of the steering wheel.  This will simplify quick glances to check along n/s of van whilst travelling.

Has anyone done this? What type of lens (field of view) is best.

Comments/advice appreciated.