I don't know where in the northeast you are, but your plan to survive with knickers through December will probably be fine. Full tights work better for me given that I'm here all winter, but you'll miss the worst of winter, so you have some leeway.
Biggest thing is just to make sure you've got protection from the wind - windbreaker, gloves, skull cap/balaclava, shoe covers, etc. With that, and a some base layers depending on how cold it is, you're fine.
And they do make balaclava shirts! Look up WarmSkin and Schampa brand - I think they cater to snowmobilers and the like.