I have used a pair of ladies calf length stockings under my wool stockings, and they work quite well to transfer any moisture away from my feet, and they are quite warm.
They are thin enough, that they don't affect the fit of your boots, unless they are too tight to begin with.
As an additional benifit, if you need a way to keep your string from hitting your sleeve, you can always cut the foot off the stocking and pull it over your sleeve, it compresses the sleeve all they way to the elbow.
Might sound goofy, but I would rather be goofy than cold. I'm sure that some of my hunting buddies would be more than happy to verify the "goofy" part.:-)