Hi Destinations -- welcome to the Forum!
I've travelled successfully in -8 to -9 C temps. Towing in similar temps you might need to burn the furnace. Don't set the thermostat too high or you'll use a lot
of LP! Ask how I know...
Set a thermometer under cabinets where your plumbing is located and check at stops while towing. That's the only way to tell if you're keeping your pipes warm enough.
Be cautious. We have seen -15 C temps by the end of Oct -- not often and definitely storm related -- you wouldn't be on the road in those conditions. We did a Lake Superior Circle Tour early last month and it seemed many provincial parks were getting ready to shut things down. Waterton Lakes & Glacier sure were shutting down by mid-Sept on a trip a year ago. So factor commercial campgrounds into your thoughts.
Water in a lot of places might be turned off in campground loops. There frequently is a central location to fill your fresh water tank. I've seen dump station rinse water not available late in the season. You'll be most interested in having an electric plug-in -- the furnace is about the biggest amp draw of anything in your Airstream. I'll set the overnight thermostat to about 50 F so that the motor is not on all the time if I'm boondocking .... and I appreciate a little peace & quiet. It's a challenge running the furnace 2 nights or more on battery power alone. And it takes multiple hundreds of miles on the road for your tow vehicle's alternator to recharge a drained battery.
Keep us posted!