Jon, I'd suggest that you separate the surrounds wider, say about 8 feet. Keep in mind that the surrounds in a 5.1 setup are side surrounds(not "rear")and play the side surround channels, even if they're mounted on the back wall. So, they should be separated as widely as possible, so as to give a primarily side, rather than back, effect. They should be about 2-3 feet above ear level and pointed directly forward, not aimed at the listening position.

Because the listening position is almost up against the back wall, it's unlikely that back surrounds in a 7.1 setup will add significantly. I suggest that generally at least 4 feet of space be behind the listeners for back surrounds to form a rear sound field.

Enjoy the music, not the equipment.