I have a pop up camper on the back of my pickup and stay in it through the bird season. I hunt from my camper until the end of the Kansas season in January.
I don't use my water system for fear of freezing it, but other than that, I am fine, especially if I can find a sheltered spot to camp that's out of the wind.
I have one farmer friend who lets me camp in his shelterbelt, and another who lets me pull into his quonset hut if its real cold and windy. It helps to find an electrical hookup if possible to save your camper battery in extreme cold and I've got several spots mostly in parks that have hookups. I just turn the heat down low and cozy up to the dog at night to save on propane.
I've hunted this way for years and it suits me fine, I much prefer this to a motel.