I'd try working with these speakers a little more before giving up.
Have you tried measuring with some test tones and an SPL meter to narrow down where the frequency humps are?
You could try the trick of sitting a foot from the back wall while damping the standing wave there with 4" thick panels (say three 2'x4' panels to start). This would allow getting the speakers well out from the front wall and still allow a decent separation for soundstage width. With the speakers along the 12' wall you could have a 6' listening triangle with the speakers 4' out from the front wall and 3' from the side walls.
I suppose after that you could try EQ with 1 or more subwoofers or an outboard digital room correction box.
Have you tried measuring with some test tones and an SPL meter to narrow down where the frequency humps are?
You could try the trick of sitting a foot from the back wall while damping the standing wave there with 4" thick panels (say three 2'x4' panels to start). This would allow getting the speakers well out from the front wall and still allow a decent separation for soundstage width. With the speakers along the 12' wall you could have a 6' listening triangle with the speakers 4' out from the front wall and 3' from the side walls.
I suppose after that you could try EQ with 1 or more subwoofers or an outboard digital room correction box.