Thanks for the pictures. I still stick with the 5.1 is plenty for the space, but if you "must have" 7.1, then as I mentioned and Dak stated too, put the one on the soffit instead of in the bar area. You would need to crank the volume up and work with the large delay due to distance and amount of air volume that the sound would need to travel through to get to the listening area.
Then again, using a pair of QS8s and ditching the in-ceiling speakers and going with a 5.1 setup will really do a lot better than a questionable 7.1 setup.
I have been wanting 7.1 for a long time, but have been totally happy with my 5.1 setup for years. In my current setup, I went 7.1, but only because I have 2 rows of seats. Even movies encoded in 7.1 (which aren't many) aren't *that* much different sounding than a 5.1 setup.
2-M60s, VP180, VP150, 4-QS8s, 4-M3s, SVS 20-39PCi, DIY Sub, 8-Shakers, JVC RS45