I really like the idea of 1 IPC per valueless allied pacific island. I am going to propose that to the group I play with, because we are always looking for a way to balance the game, but at the same time try to keep it as close to OOB as possible.
What we have been doing for several games, and it is working well, is this:
Play “cry uncle” - so no Victory City win condition for Axis.
Germany not allowed to build factories in original German controlled territories.
USA can do whatever they want in the European theater only, right away in turn one.