I used to fly in the single digit temperatures. Warming the engine with my cars exhaust always worked for me.
I tried ether once. I must have used too much The engine backfired and sent the prop right off of the engine and into my side.
Good thing it was so cold. My coat, sweatshirt, T-shirt and undershirt stopped the spinning prop before it hit skin!
Good luck out there! I'll stick to building and sim time until spring!
Doug