Good point John about pushing them out to the sides further. That is what was recommended to me back in 2004 with V2.0 of the theater where my seating was against one wall like that. I had forgotten about pushing them out a couple of feet wider than my couch.
Potential problem may be that slowdive's right surround would get pushed in front of a window...
You could go with stands for them, or what about mirroring the room and putting the main couch where the TV is and the TV where the couch is? You would be able to mount one to a wall and the other hung from the ceiling.
OR
What about turning everything 90degrees to the right. The TV is on the wall on the right of the diagram. The surround speakers could be set up more properly, however you end up with a single seat (recliner maybe) without a home. I kept everything the same but slightly adjusted the couch to allow for more walking space on the left of the couch (top of the diagram).
