The only two rules changes we are still using after several battles because useful and no disadvantages noticed yet are:The BB needs 2 hits to be destroyed but IN A ROW - So if the defender decides to take a damage on a BB > The very next hit (if any) during the battle must be one this same BB. This to avoid the 2 or 3 BB “damage shield” of 2 or 3 hits at the start of the battle. Notice that this do no weaken the big advantage of each BB to bring +1 hit point to the battle. And for example 2xBB + 2xDD will still bring 6 targets to be destroyed by the enemy instead of 4.
We play where every other hit HAS to kill or sink something. So say you get three hits on your navy. The first hit you can take free on your BB, but the second hit you have to sink the BB or a different smaller vessel, or lose a plane. Then the third hit you can take free on a different battleship, etc. Works good for us!