What's the best position for Mission M7DS bipole surround speakers in 5.1 system?

In a home theater set-up experimenting on which position to place the surround speakers is a common practice or a "must do". Since your seating area is already flushed to the rear wall I suggest you place them on the side walls and "experiment" on the height position. Try about a foot or two above your ear-level. Because of your existing environment only you can decide which position suits you. Watch an action video and let your ears decide.