Our first week in our van 4 years ago was in boondocking conditions 24/7 for a week below freezing down to 0 deg. F. with freshwater in the tank. Gained a lot of confidence in that first week. We have attended three of Mike Wendland's Winter Freezeouts in Michigan's UP in January. Those were easy because the campground had electric hookups. Most recently with the polar vortex we endured boondocking overnight in -15 deg. F. again with water camping on a city street. When it is below 0 deg. F. we consume about 3 gallons of diesel fuel in 24 hours parked with the Espar diesel-fired system. That means we can boondock almost 6 days continuously in those conditions. We can go a week to 12 days with our tanks. I would say we have a four season Class B RV. Dumping in the winter is of course an issue but only took us 5 casual days to get to South Padre Island, TX and 70 degree weather surfing the polar vortex south on February 1st from Minnesota. Dumping and washing our B of road salt in a heated space in Minnesota is now easy at our condo garage complex throughout the winter.
Hope with our next van we will be even more capable including the high heat end with boondocking air conditioning.
2021 Advanced RV 144 custom Sprinter
2015 Advanced RV Extended body Sprinter
2011 Great West Van Legend Sprinter
2005 Pleasure-way Plateau TS Sprinter