We stay comfortable. We have a full-sized inner spring queen-sized mattress that fits in the back of the suburban. Clint puts down a log to help me step in and out of the Suburban. Some of our overlanding friends sleep with their heads to the back and exit the side doors. I like exiting the back. The backdoor does not shut all the way with the mattress pulled out. It's only open a crack, so we fasten a tarp to the luggage racks and just drape it over the door. When we open it, the tarp goes up with the door. If we are staying put for a while, we do the same thing but set the tarp up as a rainfly or sun shade during the day so we can sit under it. Tarps can be used as rainflys (rainflies?) on both sides and the back of the suburban which gives a lot of space out of the rain.
Emily and Hannah have an easy setup (sets up in seconds) tent with an air mattress. We keep a new tarp that can cover their tent in case they need it. So far, they have never needed it.
Night-time temperatures got down to 20 degrees, and we were all toasty in our beds. I wear a base layer to bed. I get hot when I sleep. Clint and the girls wear their slipper socks. The girls wear a hat or put a big comforter between their heads and the tent wall. The comforter touches their head and keeps them warm. Keep your head, hands, and feet warm, and you will be surprised how warm you stay.
We have 30 gallons of pressurized water on top of the suburban for cleaning and bathing. We have a 12v pump that will pump the water from the source to the tanks. I will go anywhere as long as I can bathe and keep cooking items sanitary. We have gone without the tanks and bathed and washed dishes with the creek water. Most of the time, we heat the water and bathe behind a tarp. We've gone on a few trips where Clint and I just bathed in the creek in 30-degree temps. Those were refreshing and invigorating experiences! :-D And, I am glad I have experienced them.
To see some of the other items we keep on board, see this post. (For those who read about our first mishap and might have noticed, yes, that is a new door on the Suburban.)
We own an RV motorhome and a travel trailer. We have also had popups, a fold-up, and a 5th wheel. We have several tents. We like camping in the 4WD Suburban the best because it can cross streams and rivers to get us where few people get to go. Fast to pack up and go! Quick to set up! Nowhere it can't go! It lets us do the 4WD roads and everything else. If you want to explore natural areas, this is an inexpensive way to get out there.
Some of the ideas here came from fellow overlanding friends and the rest we learned on our own as we went out and lived it. We've seen people with brand-new vehicles and very expensive setups to people in beat-up small trucks with nothing but a cooler of food. (They slept in the truck bed in sleeping bags.)
One of our favorite encounters was with a young man in a small, old truck (no 4WD) scooting up the Bald Mountain Jeep Trail off Coal Road better than the Jeep group with him. He was grinning from ear to ear and could fit in places the rest of us could not. All of us had his back if he needed it, but he never needed it!
Dear Reader, We have more expensive options to use, but we don't use them. Our RV motorhome, travel trailer, and large 10 x 20 tents are at home and not being used. Compared to the motorhome and travel trailer, the suburban takes less gas, is less weight to haul, less risk on the road, less work, less maintenance, and gives more access to the roads less traveled. I'm sharing that so those who read this and want to get out there aren't held back due to their wallet or lack of options. If you want to get out there and do it, be creative and go do it. If your attitude is good, you will have a great time and learn something no matter the weather or experience.