I lived and flew my Stinson108 in Alaska during the 1980's. Most of my really cold flying was for the Ididarod Trail Dog Sled Race people. North of the Alaska range it would get down to 40' below 0. I have used several different heaters that I made. None required any electrical source.... all were portable. Other things I would do is: remove the battery and engine oil as soon as I would land and then put them back into the airplane when I was ready to fly (after the engine is preheated). The battery and engine oil I would keep inside with me to stay warm. Cold oil can require 2 3 times the cranking power from your starter not to mention can turn into the consistency of peanutbutter. the colder the battery the less power it can put out. It may even freeze and crack at extreme low temps.
1; Class A stove pipe. It is double or triple wall design, insolated high heat capable. at leat 18 to 24 inches.
standard single layer stove pipe with a 90' elbow. and a straight piece
weed burner torch such as Harbor Freight #91033 or #91037
Small refillable propane tank. They come as small as 2.5lb in steel, aluminum or fiberglass. This is the most expensive part of the heater.
connect the Class A pipe to the 90' pipe and then the straight section. this will look like the letter "L" the standard pipe end goes under the engine cowling at the exhaust pipes or nose wheel area.
set the weed burner at the end of the Class A stove pipe so that the flame is inside the pipe. It's important to have enough length of pipe so that no actual flame passes the 90' elbow.
Cover the engine with an old sleeping bag or quilt. I cut and trimmed mine to fit snugly with velcro. Leave a slit so that you can stick your hand through the covering and feel the cylinders.
This will put out as much heat as the $500. Red Dragon but at 1/4 th the price. Do not leave it un attended and have a fire extinguisher handy.
2. Heat rated flexible hose
short length of standard stove pipe
5Gal steel bucket, like paint, or driveway sealant comes in, with removable lid.
Coleman Catalatic heater , Coleman fuel type (these aren't made any more so you will have to look on Ebay)
Cut a bunch of 1-2 inch holes all around the bottom of the bucket. This lets air in. Cut a hole in the lid so that standard stove pipe will fit into it. Connect the flexible stove pipe to the standard stove pipe. Light the catalatic heater and place in the bucker. place the lid with the pipe and hose attached on the bucket. Shove the the flexible stove pipe up under the cowling as with the first heater. Cover the engine cowling as above. The shorter the flexible hose the better but I would still have a little curve to it so that the heating bucket isn't sitting directly under the plane. My catalatic heater will go all night on just one tank of gas and it can be left un attended. All the parts fit inside the bucket when done, easy to store and transport.
3. Exactly the same as #2 but using a propane type catalatic heater.
4. If you can find one and want to spend the money and carry around a spare 12vt kiddy car sealed battery you can get one of these:
Note: they are recently discontinued too..
Sorry I don't have any photos.
I like the electric heater that one person submitted but I can always use my bucket heaters since they don't require any electrical power.
BRENT BUNCH , if you have any questions just email me firstname.lastname@example.org