Reno, the FLA issue comes up in 210.23(A)(2) in reference to receptacles on branch circuits feeding fixed in place equipment. If you do not have in intervening OC device before you get to the receptacle it is still a branch circuit.
I suppose you might want to start the fight that the disco for the A/C makes that part of the load a feeder but I bet you don't win if the inspector doesn't like this setup.
Your other solution (2/4 box)is a far better idea.
