Also, years ago, the NCAA instituted rules about the number of assistant coaches per staff in certain sports, to reduce any real or perceived advantage well-heeled schools might gain by having numerically huge staffs.
I believe that one head coach and two assistants are PLENTY to manage/coach a live match. I'd allow schools as many staff as they're willing to pay for, but allow only 3 on the bench/sideline during a match.
I'd also rule that, as soon as a yellow card is assessed to a bench/coach, that no coaches from that side be allowed to stand during the remainder of the match.