I think the Axis victory conditions need to be more like the Allies’. So maybe simply “axis must control 5 allied capitols as well as at least 1 axis capitol for a complete round of play”. That may sound like it would take too long, but remember, the allies have to completely wipe out their enemy to win. Killing everyone but U.S. or everyone but U.S.S.R. wouldn’t be that hard. And conceding is always an option.
Another way to do it would be make it 3 of these 4: washington, london, calcutta, moscow.
Yet another, “axis must control washington, london, and moscow as well as at least 1 axis capitol for a complete round of play”. That might seem weird at first because none are on the pacific map, but to me this seems like the best option. First of all, if japan is strong enough, it is reasonable to take moscow and/or washington with them. Secondly, even if germany/italy end up taking all the capitols, this will only be possible if japan is played well enough to stay rich, destroy india, and sap resources from U.S.
Oh yeah, by the way I think the 6VC win for Japan is the cheesiest thing in G40.