Q wrote:I have one of the heaters like in the picture Mike posted. It works great down to below zero degrees.
As an old backpacker/motorcycle tourist I agree that a good sleeping bag will get you through just about any cold night, but I don't find them especially comfortable. In really cold weather the only way I am able to keep warm is to snug everything up so just my snozz is sticking out of a small hole. Hard to roll over and change positions. Then comes the worst part, getting out of the sleeping bag in the morning.
Q
My own opinion is that a furnace is overkill for your average 3-season camper who may encounter occaisional chilly nights in the mountains or at the beginning or end of their camping seasons. For people that do a lot of winter camping, I suppose a furnace might be a good investment.
I have no expeience with that furnace or any other furnace. I can't make any truly informed comments on it's safety. However, the idea of running any gas fired heating device while sleeping in a 5 x 8 foot plywood box gives me the willeys. I've been using sleeping bags since I was a kid. My gut instinct tells me to go with what I know.
Another alternative is a 12 volt electric blanket. I've seen them on the Web. Unfortunatly, I don't have the URL handy. The downside is cold weather really weakens your battery at a time when you'll be depending on it the most.
I guess the decision boils down to your design priorities and how often you camp in cold weather. And, that's the beauty of building your own trailer. You can tailer it to your exact needs.