I think this is a very interesting thought, one famously articulated by Kant: the CI is essentially a law in the style of natural law, only pertaining to the will. He agrees with you that the law can't be identified with each individual will (for one thing, some of us are bad or irrational). This avoids the 'sensory deprivation' problem, but keeps the idea that insofar as we're governed by the law of the will, we're free. The result is that we're free only to the extent that we're good.