Ben, I think you'll be totally fine with that scenario.

I'd agree that - with your asymmetrical layout and that little notch on the rear left - the QS4's might be even better than monopoles.

The location of the subs on the drawing might be ideal, but it also might not. While the walls are open, I'd be tempted to run some cable to the middle of the side walls and maybe the back right corner just in case.

bibere usque ad hilaritatem