I have noticed that half masks that you attach on the back of your head like this one seems to lead to less fogging problem than the other balaclavas that i have because I can tighten up as much as i want so that no gap remains between the top of the half mask and my nose preventing my exhaled breath from fogging my goggles.
That plus double lens goggles and no more fogging problem most of the time (except if i'm not moving for at least several minutes or indoor with the goggles on)
http://www.amazon.com/Neoprene-Half-...=neoprene+mask