Yeah. Which, as the example of Skeeter teaches us, means that we could look for a weaker link in the chain: the professors themselves. Imperius/Obliviation strategies have been discussed in the past, but Polyjuice Potion hasn't. Would that work? Dunno. Moody fooled the wards in canon, but that was probably because the fake was the only one to ever get keyed in as a Professor in the first place. Would Polyjuice let Flitwick or one of the others be replaced?