I see ship and equipment restrictments as mostly inRP tools. The way I would do things is 1ic, 2ic (as per rules) then one or two semi-leaders to take charge when others are away. Everyone else would be the same "rank" ooRP with any further differing ranks being purely inRP, and provided it doesn't go against RP, there would be as few as possible item restrictions. In, say, a heated groupfight, ooRP friendship and respect take priority over so-called rank. Ideas and agreement take priority over so-called orders.
Better to do things via common sense than rules and regs.