Build a whole bunch of Cav or Inf or Armored or Airborn, if you have the tech, and the Free Corps should fire around the time Commifornia rebels. When the war starts, the rebels don't get any regular army divisions (because you don't have any), so that one division in NYC can rush and cap the VPs around Boston very easily. Ignore the focus that keeps states in the Union, instead, beeline for Free Corps.
Disband all but one division, park that division in NYC.
