I have been fiddling around with Russian Front for the past couple of weeks.
I use most of the optional rules. But a couple go too far for me.
20.2 Strategic Bombing - At a minimum just strip away 126.96.36.199 Effects of Replacement Attacks.
19.5.2 Inverted Counters - I'm all for a limited version of this, but as written its too pervasive.
Keeping it simple: The top enemy ground combat unit and any naval unit in an adjacent hex to any friendly ground combat unit should automatically be revealed at the end of each player's movement, if not already revealed. German units in or adjacent to Russian cities should be revealed. Air units on both sides are always revealed. Of course engaged units are revealed in combat. Naval units in enemy home country cities are revealed otherwise they are only revealed during combat or if adjacent to enemy ground units. During the friendly supply phase, if a ground combat unit, that has been revealed, cannot trace a path (same as a supply path) to an enemy unit it can be inverted.
Non Phasing Reserve Movement and Combat:
I have been tinkering with one subtle variant. Added to 188.8.131.52
Any battle that includes combat units that performed Non Phasing Reserve Movement is resolved first, after all blitz attacks, pursuit and movement have been resolve, but before other battles are resolved. Some marker or other mnemonic would be needed.
Just so you know I was wrong about air supply. Do to when it is resolved during the Sequence of Play and to the Exploitation rules air supply never assists movement during regular ground movement or exploitation. It really does amount to just subsistence.