AbigailII: I'm advocating for filling in the squares that are "obviously" zero. While obvious hasn't been defined, it doesn't apply here. This is an active part of the board, and most shots will reveal some information about where the frogs are. Figuring out that D4 is 0 is something a good player would do (and a bad player might not).
I'm not trying to automate the game so that there's little actual thinking for the players to do. I'm trying to eliminate the phase where there's a 5x7 block with a checkerboard pattern of zeros, and both players spend almost 20 turns filling it in, because the alternative is to shoot in an area like what you drew and risk giving your opponent an advantage.
troydaniels: Filling in *some* of the squares that are 0 is something that doesn't appeal to me at all. If some of the squares are filled in, but not all of them, you introduce a category of chance in the game where there's no such chance currently. IMO, either all 0-predetermined squares should be revealed, or none. Not all "obviously" zero for some vague notion of obvious.