Doing that would however also solve the problem of how to flip it left to right - it's just a camera pointed backwards so a car approaching on one side passes on the other - currently very confusing.
I know in DX if you specify the viewport co-ords backwards the scene is rendered backwards - i'm not sure if Blitz supports it (at work on a Mac atm so I cant test) but you could try it:
ie: cameraviewport mirrorCam,0,0,-100,50
As for the screenies, my first words (out loud whilst at work and supposed to be working...), "oh wow, I gotta have a try at that."
:)