Hello Wyatt,
Rather than build a false wall for the W3s, which would be feasible, can you not make the entertainmnent center a bit less wide and put the W3s into the wall on either side of the entertainment center? The W3s do not have to be parallel with the front face of the center.
Are you intending to mount the surround speakers on shelves in the EC at the front? There's no point to that. You might as well listen in stereo except for the center channel. Ideally, the surrounds go on the side walls, above ear level (like in a cinema) roughly even with or a bit behind your listening area. Or you could hang a pair of QS8s or QS4s from the ceiling using the Axiom ceiling bracket. The multi-directional QS8s and 4s are forgiving enough that you could try one at the side and one at the rear. Or try both at the rear. You could also use Axiom W2s as surrounds in the wall at the sides or the rear.
If you have open shelves in the EC, you could also consider M3s or M22s on an open shelf, protruding a bit from the edge to avoid boundary effects from the adjacent shelving and surfaces.
