If the OP is unable to follow diagram #3 then the OP probably would have trouble turning on the key to start his engine.
Maybe we ought to give him a little credit for a) asking to confirm his plan and receiving that excellent link from MurrayM and Trojan; and b) for realizing that connecting the + and - on 4 batteries is not rocket science and has nothing to do with the vagaries of marine electrical systems. It is everything after the batteries he should study and learn!
Dave