I would suggest following the Xenoblade Fandom route in terms of spoilers. The way they do it is the order they come in, so a character would be The Seventh Party Member and whatnot.
Though that wouldn’t help in specific instances, especially (EP8 ???, extremely spoilerish characters that would ruin a first read) with people such as Tohya. How would it be? Author? There’s Ikuko. True Author? Those in EP 6 would suspect something. Second Creator? That would indirectly spoil that there’s two. Maybe White Man?
There’s really no easy way to go about it. Perhaps haircolor and eyes would work. Very touchy, though!