a
theatre that is quite local to me has a couple of old techno beams... on the rare occasion that i have pulled them out to have a bit of a fiddle for dance concerts that i have done there and such things, i have found the best way to position them was parallel (yeah im aware i cant spell), this way allowed me to go to the back and front of the stage and to the sides a bit, but it sounds like you are mainly trying to achieve the scanning up and down the stage.
i have never been too fond of moving mirrors, but if you pick the right spots for them you should get pretty good coverage of the area's that you wanna get keeping in mind they are gonna go further out the sides than up and down
