I have had good luck when shooting ducks in the dead of winter with the nikon anti fog cloths. One application lasts most of the winter. I think it is similar to the silicone liquid. if your local camerA shop does not have them, try a shop which sells nikon sport optics ( binoculars, scopes, etc.). Hope it helps.
That's why I kept my camera gear (except the light meter) in my sister's unheated garage when visiting over Christmas. That way I can go out and photograph at any time. Temps are usually -10C or warmer.
keeping it outside makes sence as bring a cold camera inside will get condensation all over it, but I don't find it helps keep it from fogging. I find that a cold glass fogs instantly (and then freezes over) but while its warm its fine...
I have one of Steve's screens in my Crown Graphic but it was quite dim compared to my Wista screen which is anall-in-one combination screen/fresnel , however with the fresnel I added to Steve's screen it's not far behind.