I'm just learning to use a quilt, and mine's a 40-degree rating (Thermarest Ventra). At 40 or above, a balaclava is plenty warm inside a tent. Below that, I'm thinking I'll need a layer of insulating clothing anyhow, so a Patagonia hooded down sweater. I'm hoping that also eliminates the old sleeping bag problem of rolling onto my side and burying my face in the side of the hood.