That would be horribly boring and no fun for the Japanese side...
No, I was thinking more along something inspired by it. Such as an offensive push by the japanese in frame 1 along some fictional (or real?) islands... Then in frame 2 you have several attacks/defenses as you normally would find, but that a side-goal would be for hunting down and finding a flight of 3 betty bombers with light escorts. You would have to devote resources meaning you lessen the impact you can do elsewhere, but IF found and shot down (maybe make a rule no more than 1 squad can engage at a time? others have to shadow it?) it would change Frame 3. If Yamamoto is shot down in Frame 2, then the allies go offensive in frame 3, but if Yamamoto gets through alive the Japanese are on the push in frame 3. I don't know off the top of my head about a 4th frame just yet.
This way there would be that element of Yamamoto's being shot down, but it wouldn't be the only thing. It would change the event, but NOT end the event or pre-determine the event.
That's what I had in mind, or something like that.