Hi Namax,
If you get our quadpolar QS8 surrounds they don't have to mounted opposite each other and they are very forgiving of non-symmetrical placment. You might try the beam. You'd have to keep the top woofer of the QS8s away from the ceiling, but apart from that limitation, they should produce an excellent sense of envelopment for the listening area.
Alternatively, you might try bracket-mounting them above the doorway to the side if that's possible. Surrounds work best placed to the sides of the listening area, but the QS8s are very flexible because they radiate in many directions. Check out omnimount.com and vogelsusa.com for custom brackets.
Regards,
