You were safe to turn around within the marked out photo area, though as you were being lit with flash guns, your sillhouette would've just been a picture of your bum!
We'll have to experiment with mirrors/previews, the light of a preview screen may upset the photos, but it may be too dark to see yourself in a mirror! Maybe a screen showing the last shot, with a blackout switch on it?
We will experiment, if demand is this high again, we may find we can offer more than one session as well!