Kyle,
I have a very similar layout, believe it or not. I placed our surrounds high on the rear wall. It actually worked out very well. Set up your fronts and centers around your tv, an mount your rears high on the back wall. Not familiar with your equipment though. I would suggest making some temporary mounts with some drywall screws to wall studs and mount your speakers. You can then calibrate your speaker levels with a RS sound meter and set your distances on your receiver. You can then shift the speaker locations around a bit (recalibrating your levels and distances for each setup) until you find one that sounds best from your seating area. Once you get your speaker locations worked out, you can then figure out how to run your wires and keep them hidden.
Hope this helps.