It is not a design, but putting a SEOS-12 above 4 NS6's in a square pattern would be quite the speaker.
If you don't mind a very wide box, Bwaslo has a design with 4 NS6's in a horizontal row below a SEOS-12. It should be an extremely high performer.
If you can design your own or measure and use DSP, a SEOS-18 over a 3x3 matrix of NS6's crossed around 900hz would be pretty wild. You could even do a 4wide x 3deep matrix with shading on the outer woofers. That would be pretty wild.
In the "absolutely nuts" arena, a 5x3 array of NS6's below a JBL 2384 horn (from 4722) crossed around 600hz. It would likely need a little shading on the outer 6 woofers. It should control horizontal directivity down to about 300-400hz. That would be hard to beat in a 34"h x 30"w x 16"d enclosure, if that works for you. Behind a screenwall it would be killer. Fill the open spaces with sealed subwoofers.