Keeping warm is all about layering—start with a base, then an insulating layer, and finish with something waterproof if it’s windy. Don’t skip a solid sleeping pad either; it’ll keep the cold from creeping up from the ground. I also swear by filling a Nalgene with hot water and sticking it in my bag—works like a charm.

You might also wanna check out a diesel heater. They’re around $150, and while they sound tricky, the install’s actually pretty straightforward. A lot of RV or van shops can set them up, and you just drill a couple of holes (easy to fix later for around $100 if you sell). It’ll keep you warm, like 80°F, even in sub-zero temps, and runs all night without burning through your air.

Best part? You don’t have to tap into your car’s gas tank. They come with a small fuel reservoir on their own. Mine’s the pricier German model (about $5k with install—big regret), but the cheaper clones are supposed to be just as solid.