On edit: I just noticed the camera system I bought has apparently been replaced with this on:
https://www.amazon.com/gp/product/B00VJJ261C/?th=1
The Esky 7-inch dual camera system I used is currently unavailable on Amazon, but here's the link for it:
I made a filler for the original dash opening from some scrap plastic painted to match and attached the monitor to it. The hardest part was routing the two cables down to the frame and up the rear cap to the original camera location.
The system has been in use since 2014 with no problems until recently when one of the cameras started fogging up. My examination found that a seal on the camera had failed, allowing water into the housing. I found a similar plug compatible replacement on Amazon for $32.