Two comments if I may. All Japanese CA's were designed with treaty limits in mind. They may have cheated, but still they were limited. The German Hipper Class were big cheats at 14,000 tons, but that was partly from their heavy turret design. The Baltimore's were based on a treaty era design, freed from restrictions, and they came in at over 14,000 tons, and were far more capable then any Japanese, or German CA's. The Des Moines came in at 21,000 tons full load. It would be interesting to imagine what ships would have been built if WWII didn't start till 1944, which is when Hitler told his Military Leaders he planed to start the war.
Yes two rudders are a great idea. I served on a Leahy Class CG, small by WWII standards at around 7,800 tons, and we had a two rudder system. We could make some radicle high speed maneuvers. What I remember most was the steering gear leaked oil like an SOB. I've always found it hard to understand why the Bismarck couldn't maneuver using her screws, to at least make headway towards France. Even at 10 kts she might have gotten away. Rodney, and KGV were very low on fuel, and were sailing at an economical speed, if Bismarck was 110 nmi further away The RN BB's wouldn't have caught up to her till the following night, and might have had to turn back before then. Maybe someone has more information on this subject?