I don't see a way beyond a layer mixer and a key, sometimes with masks. You can do curves and secondaries before that to make it a little more predictable, and if you were trying to preserve precise hair color, multiple tracking windows (or even attached VFX masks) could help clean them up. There are shows and films out there where they essentially cut the characters out of the background and correct everything in separate passes (ala The Revenant), which would be one way to exercise extremely precise control over every facet. But it's very time-consuming. The beauty of Stranger Things was that it had vastly different looks in different parts of the show: the kids' homes looked one way, the evil laboratory looked another way, the daytime streets looked very "normal" most of the time, the school looked yet another way (but still normal), the "upside down" dimension had its own definitive look... there was no one look, and certainly no consistent orange/teal. Skip Kimball at Tech did a terrific job on it, aided by the cinematographers.