Not guilty of modalism (possibly)

My formulation of the doctrine the Trinity as describing one God in three presences, rather than Persons, is, of course, open to the charge of being heretical on the grounds that it could be construed as a form of modalism or Sabellianism (the view that God is one Person with three 'modes' of existence - eg. that he existed originally as the Father, then came to earth as the Son and is now present with us as the Holy Spirit - as opposed to three Persons, each of whom exists as the same one Being). My only defense against this charge is to point out that it all depends on what is meant by the word 'person'. I don't know what the word 'person' meant to somebody in the Greek speaking world of the 4th Century. I understand that the Latin word 'persona' (from which we derive the English word 'person') is itself derived from a Greek word which originally meant 'mask' (as in the mask worn by an actor on the stage). Clearly, at least in its original form, it did not refer to an actual, individual self. However, our modern understanding of the word 'person' is that it refers to a conscious, self-aware subject or agent. In grammar, the subject of a verb is the one who acts while the object is that which is acted upon - so if God were three subjects then we would have to say, for example, that 'they created the world' rather than that 'He created it'.
Since none of us know exactly what the word 'person' meant to the people who devised the Nicene Creed or the early Trinitarian formulas, it is at least conceivable that they may have meant something similar to what I mean when I say that God is present to us in three different ways - that He exists as one self with three distinct presences, namely His transcendent presence as the Father, His very personal presence in the life and teachings of the man Jesus Christ and His immanent presence amongst us by means of His Holy Spirit.