We have camped in 17 degree nightime weather in the Rockies, during the day it was around 30 degrees. The next night we woke up to 3 inches of snow on the ground in Idaho. We stayed a couple of extra days to wait out the snow. Once it cleared we headed home to the Washington coast where we found moderate weather.
The point made earlier is correct, heated tanks but not the water lines. We did just fine with the cabin heated and no external water connected. One of our neighbors at the Idaho campground connected to city water and left it overnight. The hose and pipes froze and his Motorhome pipes cracked.
Traveling in cold weather isn't for everyone and it does have it's risks. Leaving it winterized is probably the safest approach. However we have been OK when we experienced colder weather with the tank heaters on and the cabin heated. Safe travels!