?
Seems to me that attaching speakers directly to a tv would remove the advantage of stereo separation, and you'd be better off with a sound bar, like the Atlantic Technology offering at Outlaw Audio for example.
As far as brackets go, the only thing I'm aware of is a center stage bracket.
What did you have in mind for fabrication? Think you could telescope mounts far enough out to restore stereo separation? Maybe you could use wall mount brackets, but screw them to a long board attached to your tv's mount. Or something.
Sorry, I'm probably not saying anything you haven't already thought of.
How come you're avoiding wall mounts anyway? Is it the holes in walls voiding a security deposit thing, or the wires hanging down thing, or something else?