How you are talking, I kinda assume you are talking about using your TT in the driveway during the winter months. No issues, Might want a dehumidifier, or damp rid, and some heat.
Now if your talking going camping; How cold are you thinking of going out in? If I stored my TT at home in the winter I would go out every month. Most of our SP's keep a some spots plowed.
Condensation is a big issue, We keep the bathroom vent open year round (about 1/2-1 inch) and have a max air cover. Some people run a small dehumidifier. To keep condensation down, watch what you are cooking, it can add a lot of moisture into the air.
What is the issue with towing in the snow. So they put salt down. Only thing it will affect is accelerating some surface rust on the undercarriage. You still drive your cars in the snow and salt right? Have you looked at your vehicles undercarriage protection. It is pretty much the same. Big thing is just being careful stopping, plan ahead, have the TT brakes set right. I have towed many times in the winter, and have jackknifed a utility trailer while backing up (not sure what happened there???)
Use it, enjoy it