I'm very new to growing, so what I'm about to post is probably going to sound stupid, but when I used to visit my grandpa in Mexico he would boil water to keep his plants warm. He also built a PVC tent/greenhouse for his plants. When you brought up the Coleman stove it reminded me of him. I bought him one for his bday a few years back before he passed and he loved it. I don't know if it helps you with the moisture from the H2o vapor , but I do know it heats up a tent/greenhouse.I’m just north of the 49th and a carport frame might work. Nope I didn’t use mostly manure, so keeping them warm will be my biggest challenge. A cover will keep them dry.
Was thinking my coleman camp stove hooked up to a 20lb tank. Would have to dial in the temp for sure. But that would create some heat for them!!