For the most part, unless the time of day is integral to the show, it probably will not matter what angles you use to shoot through your windows. You dont have to define an east and west for this
effect to work. All you have to do is decide how you want the light to look on
stage. For that matter, you might be able to use the same lights for "morning" and "evening" as the quality of light and relative angles are the same. You can also take advantage of amber
shift in
incandescent fixtures to tell some of the difference in time of day.
As far as
unit choice, I would use an
ERS rather than a
fresnel or other
wash fixture. Why? Control. If this is going behind a set and there is a
backdrop US of the set then I would want as little
spill as possible. I would cut the beam right in to the framing of the window. This will minimize any
bounce onto whatever is US of the set.
For positioning, as I mentioned, unless t is integral to the
plot or you really just want to do it, you could get away with hanging all your fixtures at the same elevation and just changing the SL/SR angle. This could save you from building booms and trying to mimic angles and stay out of sight lines.
This may be an
effect that you have to
play with a little nd make sure that you get the shadows that you want. Yu may find that you don't get as sharp an
image as you might like in which case you may want to look into a
template option.