Pretty cool rig
If you ever have the opportunity to go back there again, I'd recommend utilizing the rear curved wall in a more optimized manner. Hard to tell from the pics, however boundary cancellation could easily eat up a significant amount of your capability in the 35hz-45hz range. If there was a way to load the acoustic output of the subs as directly to the rear wall as possible you may have much less 1/4 wavelength destructive cancellation.
I'm sure the LF was bad ass, but if you eliminated the negative acoustic elements, it could be spectacular, much smoother response, and more efficient. If the subs are say 8 feet off the back wall, you're going to have a cancellation center approximately at 35hz. A spacing of 7 feet, 40hz, a 6' space, 47hz. So best practice would be keep them quite close, or quite distant. The range between 10' to 3' is problematic.
As you know;
1130/freq=wavelength in feet
So, if a sub is 1/4 wavelength away from a wall (especially outside because the boundaries are simple, and well defined), you'll encounter cancellation at that frequency.Here's
one article pertaining to this.
Best of luck
just found another link here