I just noticed this thread since it was brought up again. I don't want to sound sarcastic or anything, just trying to get a handle on things...
I've lived in a cold climate all my life, the past 7 years in a VERY cold area. -35 is fairly common in the winter, and some of the places I've been is colder. While picking up my M105 trailers it was below -40 in northern Maine. I don't know of anyone who goes through what you have to run a vehicle in the cold. Using modern batteries, they will work fine at those temps, no heater is necessary. Once the truck is up and running, and the batteries are getting charged, they heat up slightly on their own.
Coolant temp: You are trying to raise the engine temp too high. Diesels naturally run cool. You almost have to work to make them heat up even in the summer. My Cummins 3.9 I swapped into my Durango uses the original V-8 radiator, has a 180 degree t-stat, and still only runs at around 150 deg. in the summer, and hardly ever goes above 130 in the winter. It runs fine, and puts out plenty of heat to keep the vehicle warm. Even while idling up in Maine at -42, while we were taking a nap when we first arrived, it kept us at a reasonable temp. A bit cool, sure, but there was no load on the engine, and the Durango has a lot of space to heat up. And thats with a 3.9 liter. My opinion, the electric fan was a good idea, but don't bother going much further.
Engine heaters: My Ram with the 5.9 Cummins has a grid heater and coolant heater, nothing more. (grid heater is to warm incoming air during startup). Its never failed to start with just the factory coolant heater plugged in. My 3.9 Cummins has a coolant heater and oil pan pad. I've only ever used the oil pan pad. Its the most effective, as it thins the oil and warms the bottom end of the engine. The worst part of a cold start is trying to get thick oil moving, and thats what puts the most strain on the starter.
About the most I would do with a Deuce, would be to use the spin-on oil filter adapters that keep oil at the filters when shut down; use synthetic oil for an easier startup; stick-on oil pan heater (largest they make); keep the radiator blocked; and make sure the batteries and connections are all good. In addition, the electric fan is a good option. Besides all this, the most important factor is the FUEL. Using heated filters and fuel lines like what the veggie oil guys do might be a great idea. Keep plenty of Diesel 911 on hand, I use a half a quart for my 20 gallon tank and its never gelled on me. Only time my Ram gelled was when I was dumb...didn't use additive the last tank, let the tank get very low, and it froze on my way to work.
Just my
, lots of ways to prep for the cold. But I've been around diesels, and have learned a lot from the northern loggers. Even they don't have much they do to prep their equipment, and they have to stay parked out in the middle of nowhere.
Jim