My room is of similar size and layout and I have room for 7.1... and two rows!
Do you mind elaborating or perhaps a picture or two? Thanks.
Lots of pics in my sig...
My first row is ten feet from the front wall, perfect for TV and immersive for projection. With the room 18+ feet deep, there's room for a second row behind. Side surround speakers on the side walls and rear surround speakers in the back wall, all far away from the front row so no speaker is ever screaming into your ear.