Have now made my mind up about buying this PJ. However, being a newbie am thinking about screen size and throw pj position etc. Has anyone fitted the same pj in a room approx 4.5 from rear wall to screen. What kinda height will it need to be mounted? How much can i offset it to one side. (Ideally would like to put it on a shelf in the corner of a room.) Any help gratefully received.