I've been pondering a small stove design for heat since some of my favorite camping sites have been non electric. My small stove became a charcoal stove for safety and convenience. I can't remember who I should give credit but I saw that a Wiley Window could have it's glass replaced with any panel.
My design would have a steel panel for the window. A box would be welded to the inside of the panel. The outside of the panel would have the door to the stove. A short chimney would be removable on the outside. Charcoal briquettes could be dropped in through the chimney. A thin fiberglass insulation on the outside would save the heat for the camper.
This is just a random idea for cold weather. If we have electric, we use an electric blanket. Cozy! :-)
Tt