Of course I understand your proposed solution which, as you note, is not new- placeholders were common in Morse Code and serial comms transfers to express values with no native equivalent- but it's a created solution for a created problem, and it's more complex than almost any imaginable alternative. Sorry but it's really not very interesting to "debate" whether placeholder conversions at both ends are easier or better than simply transferring the value.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1