Jason,
Your QS8s should be mounted to each side of your listening area and slightly back. Our ear/brain interprets lateral ambient sounds much more precisely and effectively than rear emanating sounds. Try suspending them from the ceiling or using the wall on the right for one QS8 and some other arrangement (from the ceiling or a QS8 stand?)to the left of your seating area.
Ideally, they should be from 3 to 5 feet above your ear level when you are seated, and they do not need to be pointed down. You shouldn't "hear" surround speakers per se, but they should generate an enveloping surround field with well-mixed movies.
The back location for surrounds should only be used for the extra surrounds in a 7.1-channel setup. The QS8s do not need to be at identical heights or even exactly opposite each other.
