Is ceiling mounting not an option? In my home theater, I only had one wall along the left side of the room, the rest is open into a bigger room with no walls. In this picture you can see my right-side surround and my right-rear surround.



M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85