I have started buying an IC in Manchuria on J1, along with 2 transports. I find it so valuable in getting China eliminated and gone from the game. I then build 2 mechs and a tank on J2. They can reach anywhere in China on J4, except Sikang. Life is good for Japan if the Chinese are bottled up in western Tibet!
It is also nice to be able to build transports in SZ19 so that they are out of range from the Hawaiian fleet.