Mounting options.
What about one of the Axiom speaker stands for the left side? Also consider wall mounting the right speaker on the wall and using an omnimount type bracket to hang the left speaker from the ceiling.
Form what I have read, the QS8s will be much more forgiving in terms of placement than a direct radiating speaker like the W3's. If you must stick with rear wall, QS8s mounted at the rear "corners" angled towards the listening position with the Axiom Full Metal Brackets will probably work well.
I would also email or call Axiom because they have great customer support.