I wound up buying some more Hestra stuff. I bought their quallofill heli glove liner and also a pair of their Power Dry liner gloves. The liner gloves fit well into both the mitten and the glove liner, and each of those fit well into the mitten shell. I can remove the mitt and liner and the Power Dry layer stays on my hand. Total weight of all these pieces is 13.7 ounces.

I tried the mitts out this morning. As luck would have it, we had to evacuate our building so I got to stand around outside for half an hour with the temperature hovering between 0F and 10F. Fingers felt the cold, but they did not get cold.