Seems that people mostly use a small radiator with a fan to heat their campers when the heat source is hydronic. My camper is rather small and I am thinking that baseboard heater pipes would work well enough and require no fan. I could install them along the edge of the floor in my camper. That would be about 15 feet of tubing. Or even double stack them for 30 feet. That or I had another idea to use an old intercooler for a turbo engine with no fan. I feel like placing the intercooler facing up would create a convection current and naturally draw cooler air from below it and heat the entire camper. This would also be a more compact and cheaper option with less plumbing.