My memory recalls that it had something to do with compositing so that makes sense.
Yours was one of those instances where by posting your results and THINKiNG that I knew your approach I explored a completely different approach.
And the answer to that other approach is: Multiple Light Projections (with or without image gels (rotoscopes)
There are a few 'tricks' that have to be used in order for the light not to bleed to the other side of the mesh as well as a caviet on use of projected images.
For relatively flat meshes the process is rather straightforward:
(All within the same model)
Place one light (klieg) on each side of the mesh.
Adjust as appropriate (to maintain a mesh that is as flat as possible).
(Then make all mesh curvature adjustments in an Action... I haven't tested poses but those should work)
The lights can be placed outside the model but in many cases that defeats the purpose of adjusting the mesh (in an Action) while maintaining the two sided projections.
This could be done via constraints but when the lights are inside the model they get automagically constrained for us.
A second trick (more often than not) is required to keep other models in a Chor from receiving the projections on our target mesh and that is the use of at least one Light List.
This takes advantage of the fact that when a light list is first created we have the option to exclude other lights from models without light lists.
A specific downside to the approach is that meshes cannot be overly curved without risking bleed from the other projection.
A possible solution to that would be to add additional lights to account for those specific areas.
Another downside then is that the target mesh in most cases will need to be a separate model.
In order to be of much use in animation this will require constraining that mesh to another object in the Chor.
In most cases the model itself should not be adjusted but rather adjusted in Action or Chor as this will maintain proper light projections to maximum extent.
In other words, the adjusted mesh doesn't lose the projections as easily when the original model maintains its flatter (or linear) curvature.
The issue I was having with the image reflections related to trying to add the image directly to the light rather than the intance of the light within the Model in the Chor. The image appears to be applied correctly to the light but it isn't. The Tech Ref got me back on track with regard to Right Clicking on the Light and selecting New/Rotoscope. I'm not sure why we can't just drag and drop an image onto a light... but that's just not how it works.
And while I haven't experimented much the colors and images can also be animated.
Edit: An added 'gotcha' I'll have to investigate... light gels within models don't appear to save. As such they have to be re-reattached upon opening the Project again.
Ah the joys of living on the cutting edge.