Corvus, I’m literally at the edge of Zone 4/Zone 5 though we get Zone 4 lows often enough to just go with Zone 4 plants. I tested my solar oven a few years back on a January day that was about 15 degrees out and was able to cook a simple meal. The trick was keeping it properly aligned with the sun. It required frequent adjustments given how low the sun is in the sky in January.
Some could tough it out without a wood stove in the frigid north, though it won’t be a lot of fun. Your comments remind me that concerning the problem family I discussed in this thread, last winter the loser son lived in a pop up camper butted up against the north side of the garage. I assume he must have had an electric heater in it but still it must have been a challenge given how cold it was and pop ups like that not having any insulation at all. Word is that he lived there on account the old woman can’t stand him.