OK, I like your fan idea. I think you should be good to go with it. I'm really hesitant about anything to do with propane heat for anything to do with painting though. If you can be sure you won't get condensation, it's up to you whether to use it, but I can't recomend using it in good faith. There are simply too many variables, and I've never had any luck with it. Something I thought of last night as far as technique goes that I hadn't mentioned. You may already know this but when you are painting up higher - eg. - going over the hood, roof, and trunk. It's best to run the air hose over your shoulder and along your arm. It gives you a little better control over your gun and helps keep the hose out of the paint. It also helps considerably with fatigue, simply because you're not fighting the weight of the hose with your wrist. You may have already known this, but I thought I'd mention it - just in case.