i've got some waterproof oversocks. they're nice in cool wet weather. In cooold weather my feet sweat and the sweat gets cold (I'm guessing thats whats happening to you inside your bags). Under 30deg I wear them with one pair of socks under and one pair over. I'm good for my 12 mile commute but any longer and my feet would be totally frozen.
I think the best setup would be, from inside out, wicking liner socks (or anything not cotton), heavy insulation socks, water/windproof oversocks. increase internal layers as needed.
The ideal would be to keep wind/water from entering but to get sweat moisture out as fast as possible.

tim