Our definition of "Cold" up here in Saskatchewan is probably quite a bit of different than "cold" down in Tennessee. Cold up here starts about at -10F to -40F. In your type of cold I would probably be sitting by the pool wearing a banana hammock sipping on a Majito.
I used ether in extreme moderatino and it caused me head gasket damage and other loss of compression. I do not recommend using it at all.. If you do, just a little squirt while turning the key at the same time (two person operation)... Just ot get it there. WD40 is much safer and less potent...
heres a old trucker trick, take a bag of charcoal, and dump it in a pan or take some aluminum foil and make a pan, fire it up and when the fire stops blazeing slide it under your engine on the ground. block the wind from blowing under truck and in about 20 minutes it will be warm and start right up.
My father in law used to be a logger and used the "warming fire" trick all winter to get his skidder running. This was before the days of being able to hook it up to a running truck.
As far as cold starts, here in northern NH we have already had a couple -20 mornings, and my trusty Cummins started right up using the grid heater. I think it would have started without it, but I like giving it extra help. I'm shocked by how well it starts in the cold. MUCH better than my '96 Ram.
As for the ether, I wouldn't take the chance with an expensive engine.