try either: get russia attack manchuria, england attacks kwangtung with india. then US builds two IC in two pieces of china. US + UK has to fly fighters and transport man through white russia to help holding russia + China - this is kind of a remake of history - holding china at all cost.
or you can do the UK one - russia retreats. UK retreat india to persia build IC there. (yes only one but better than nothing) then later build another one in egypt if you can like a middle east belt of IC to hold off germany + japan. US fights german + japan as well

i think letting Japs do what they want in asia is a foolish idea for the allies. Recalling in real history that it was the chinese who literally drained the japs off it is evident to see defending china is important. those two are the only US land on mainland and it is important to keep them as long there as possible.
things to try for allies:
Russia attacks manchuria, move moscow infantry (about 3 more 4) towards china
England attacks Kwantung, fly mainland planes and bombers towards china
US buy two industrial complexes in mainland asia. Move SingKing infantry (1 or both) forward. fly bombers and fighters towards China. Move navy towards west coast (going to help Brits to defend Africa)
Russia move the infantries into SingKing
China to stand at all Cost! This was partly the reason why allies won the end in history(i didn’t want to imagine what the world would have become if China had succumbed/surrendered to Japan within 3 months as the japs hoped)