I don't know if it's been suggested yet. Guns of a same type ought to be slaved to yours. Maybe only one side, but it would be worth it IMO. Especialy if we get to fire them separately. One guy could then effectively shoot two or three batteries at effectively 2 or 3 times one battery's ROF, so he could range targets more efficiently.
Maybe as two modes of fire (staggered, all at once), or by mapping slave batteries 2, 3, etc to buttons/keys?