As you recall "[Rabbi] Aviner advised female teens to prefer Sherut Leumi (national service) over service in the IDF, reminding them that there were no women in the armies of Moses, Joshua, Saul, David, the Hasmoneans(*) or Simon Bar Kochba."
Ok, but so what? Once upon a time women didn't serve in the army, and the Jews won wars. Congratulations. Later, Women DID serve in the army, for example: The 48 War, the 52 Conflict, the 6 Day War, the Yom Kippur War, Sheleg and Tamuz. Aside for Tamuz, and maybe Sheleg, the results were good. Can't we reason from this, that God does not abandon an army that enlists women?
(*) I'm waiting to hear from my expert on whether or not women carried arms alongside the Maccabees. S/he thinks it might be otherwise.