First of all, do not take advice from the person who told you that a non-night vision camera will not work with a night vision monitor. They are unqualified to give you any advice. Night vision cameras just switch to black and white. All of that is done in the camera and has nothing to do with the monitor.
Secondly, yes the night vision lights do tend to reflect off the lens when it is really dark, but when it is just getting dark, its OK. I assume your existing camera is in a tube like housing. I would suggest removing the tube type housing and just mounting the camera directly to the top of the coach.
As for cameras, try to find a CCD camera, rather than a CMOS camera. They have much better contrast, and much less color spill. I am using an older version of:
http://www.rearviewsafety.com/home-page-featured-products/rvs-770613-rear-view-camera-system-backup-camera-trailer-rv-cam.htmlFor the price it is decent. Its got a few extra features that mine does not have.