About the only what if scenario would be......................
A Japanese invasion of Hawaii based on their success after the attack. Of course we know there were no Japanese transports anywhere near Hawaii. In Dec 1941, except near Wake Island. You could still simulate this with 6 IJN CV's
3 USN CV's, and some bases on the Hawaiian Islands.
Give the U.S. the Boston to simulate the early B-17s, but maybe just at one base. Anyway as always the setup would suffer from a lack of Japanese pilots. The 325th FG would fly Japanese for this setup on it's regular Tuesday/Thursday night squad nights.
Don't give the USN any cruiser task forces, and give the IJN a couple to represent their surface force advantage at the start of the war. Thats about the only ideas I can offer.