In the reality of real life there would be more tools at my disposal - like sending a couple of spare men and guns there before the outbreak of war.
What prevents you from sending more divisions down there before the war to keep as a reserve force and use these instead once the equipment and manpower levels of your starting divisions on the front start to get low?
That's essentially the same thing as sending down extra men and material in advance is. Since there are several supply areas you can even keep them back and not overload the available supply at the front.
Attrition would finish them off. 0 org kind of makes it difficult to fight.
Attrition means gradual loss of men or equipment.
0 Org is something completely different. With your proposed rules the units encircled would give up due to 0 org indeed, but with full equipment and fresh tanks from the Ruhr factories delivered just hours before surrender even if they have been cut of for 2 months.
But you just pointed out another flaw that should be fixed. Division reinforcements should be multiplied by their available supply. If a unit only has 10% supply they should only reinforce at 10% of the normal rate.
Division reinforcements getting slowed down by available supply ratio is a great idea I can get behind.