Enclosed, vented propane heater?

What i mean is something like a wood stove, where the combustion occurs inside of an enclosed metal box, which is inside of the van, and is vented out through a pipe through the roof. The box is airtight, so air inside of the van can't get in, and the combustion byproducts can't get out to the air inside of the van. Air intake is through a pipe going through the floor. A small (5-10 inch) fan could blow on the pipe going through the roof to distribute the heat inside of the van. This way, no humidity or CO is inside of the van.

What I don't mean is running a propane heater inside of a van. I know not to do that because of the humidity and CO dangers.

Anyone ever do this, or does such a product exist?