I can't do sides, due to my room layout.
What's the room layout that prevents you from using the side walls? Is it because as you stated later that the couch isn't centered left-to-right in the room?
As everyone else has said the QS8s will be fine on the rear. The only thing I was thinking is if you could find a way to put them on the side you could keep your current speakers to make a 7.1 system. That is what I've done, of course now that I've heard the QS8s I'm in more of a hurry to replace my 15 year old Sonys on the rear with something Axiom.
