If you are towing your Montana from point A to C (camping destination) and area B is cold, real cold, such as 20-32 degrees. Does the Montana have to be winterized for that trip through B?
If you are bouncing around and in movement. I would think ok, unless in that cold temperature for for than 12 hours. Drain your water low points and execute those other protective measures we are familiar with such as using a compressor to clear water lines.
We have never winterized our rig, but we full time. Saying that, we have pulled in below freezing a number of times, but we run our heater when doing so. We are lucky that all the furnace registers are fully exposed with the slides in, so there are no restrictions in the heating system. If your rig has fully, or mostly exposed registers, I would think you would be just fine with the heater running.
I would not worry much about inside stuff but low point drains and the convenience center could be a problem. I froze and broke something on the water heater bypass on a trip between Kansas City and Tucumcari, Nm. It was not really cold only about 25 degrees. There is a lot of wind chill and things are not sealed up all that good. Pump a gallon of RV antifreeze through with your winterize thing in the convenience center.