Against my better judgement, tried again and still just don't see how this is possible.
What happens
every time is that
just when I am able to win (and hitting lack of supply), japan naval invades me, surrounds me, and proceeds to overwhelm me.
I really think the supply changes now give you a seriously small window - if Japan pushes too far into China, you just don't have enough supply there to push them out, and certainly not enough factories to reliably build rails/supply hubs.
Edit:
Here's an example of what I end up facing. MASSIVE defense values while I'm out of supply:
View attachment 784187