I don't see why one would need 7 at one time.
Hard to cultivate a 4' wide stretch with 2 shanks unless you have a 24" sweep in mind.
MKK.. what problems do 10" sweeps pose? My idea was to use 4 in the front gang with 5" of space between them tip to tip and 3 in the rear covering that space with 2.5" overlap on both sides.
Ian