We go out in the Winter if the weather is fair, meaning 40's or 50's and sunny-ish. But if it's below freezing...forget about it. When we go out we just don't use the water and we have a small 5 gallon Thetford port-a-potti (leftover from our T@B teardrop days) we use instead of the toilet. It's actually quite handy because to empty it you just carry the cassette to a toilet and dump it and the Thetford usually will get us through a long weekend. Fire up the furnace and life can be good in the Winter, too.
We have friends that join us many times and we even have friends in Indy that go out even below freezing! We were out this year once in January & February and a few times in March. The biggest hassle is hooking up the batteries for just a weekend, but for those of you who store your AS at home and can plug in, you don't have that hassle. Some friends are concerned with salt on the roads in Winter but unless the roads have been freshly salted or it's slushy out I trust the clearcoat will save the day just like my aluminum Ford F250. So far no salt related issues.