I like to travel and spent 6 months in my truck camper last year and covered 20,000 miles.
My coldest night was 9°F and I was perfectly comfortable
Unless you are handicapped or gadawful lazy you should have some income. It's easy to find a pickup truck and nearly as easy to find a good truck camper.
My Bigfoot 3000 series is rated to -20° and was used by the a Canadian Mounties above the arctic circle. I've injected foam in the spots that were missing insulation and added solar panels including two that are place on the nose for winter sun angles and shedding snow.
I won't go into a lot of detail but the key thing is you can make it better and modify it to suit you. My goals were reduced propane useage and enough power to run a TV and electric blanket. I am just as comfortable as in a home.
I threw away my tent and rear seat and started camping (not living in) a K5 Blazer, it quickly became apparent that I needed a 3/4 ton or 1 ton next time around. I went with a 1 ton diesel and a Leer cap, planning to upgrade as I cut more money.
Going from bare minimum--a Blazer with an ice box, futon
and down comforter to a Truck camper and I ask myself why didn't I do it sooner. I was cheap. I wish I financed it and had it sooner.
Final thoughts. Get a diesel and extra large fuel tank. Driving slow 55-60, I get better fuel economy than most and that is unimportant except fir one thing. Good fuel economy and a large tank mean range. Once you leave the interstates it's nice not to worry about fuel. Lastly if your camper is comfy, you won't be in a rush. Pull over when trafficking c is bad and wait it out watching pre recorded westerns on your TiVo willor sleeping. The more comfortable your camper the less of a hurry you will be.
Good luck and I recommend Bigfoot campers