Your description was excellent. I feel I've got a reasonable idea of the room. Couple of quick thoughts. I'm not sure exactly sure what concern the alcove raises relative to placing the QS8, but they are VERY forgiving when it comes to placement. Some have them placed at odd distances from the listening area, even at different heights, which can be compensated for in your receiver's speaker menu. You might try a little experimentation to see if your best placement will yield satisfactory results.
Also, you mentioned having your HTIB surrounds on a shelf. Several of us have our QS8s on a shelf, propped up on anything that looks decent. The bottom woofer only needs roughly 3 inches of space to work adequately. Again, experimentation may provide an answer.
Good luck.
