Decided to post a little project I've been considering. A few months back I started tinkering with an idea I've had. Picked up a used camper last summer. Heater works great but I need other options as well. Propane will only last so long. When it warms up I'm also going to figure out how to use wood to heat it. I won't put a stove in it for many reasons. The stove will go outside. But that's later. Solar is what I'm trying to figure out now. It needs to be as light as possible. Easily portable. Relitively easy to setup. Passive or a limited mechanical system. Thermal mass as heat storage isn't an option unless the camper gets parked for an extended period of time. Then maybe a pile of rocks or small swimming pool insulated somehow. Anyway, here's where I'm at so far. I played around with a few sheets of plastic taped together. Stuck a 12 volt fan in one end and measured the heat output at the other end. Wasn't as good as I was hoping for but a 20 degree increase isn't bad. Obviously it doesn't have a baffle system in the collector. Not sure how I would accomplish that using thin plastic. It would be fairly simple to either tie into the existing duct work or install some new ( I'm leaning toward new). I was surprised at how much restriction ducts cause. Having played around before with fans and flexible 4" vent pipe suspended above my outside firepit. The air would need to be circulated through the system. Air from the camper. Through the collector, then back into the camper. That way it should keep increasing the inside temperature more effectively rather than using cooler outside air. Some issues I see with this idea is locating UV resistant plastic. Well, black anyway. Greenhouse plastic is easy enough. Insulating the underside (large heat loss without). Bonding the plastic together and wind. Simple thermostat should work OK. Power will come from the camper battery after I get the solar setup. Wondering if I should scrap the plastic idea and go with something more ridged. Foam board? I looked online for something already made. I just assumed somebody must have had this idea before and was selling them. Like a large air mattress. No luck. So please have at it. I'm open to all ideas and suggestions on improving this concept.