I don't remember much about the winters in that area of the country, E.W. and W.I. fluffy snow IIRC,(I was 13 or so when I left Cheney...many many moons ago) but I doubt you would have many issues starting due to cold fuel there. battery? yes, starter? yes, fuel... doubtful. power service white should easily handle it.
did you test your glow plugs prior to installation? you could have a few bad ones out of the box... test them with ohm meter, and verify resistance is good.
a good MB battery should crank that motor for a full minute without slowing down. it's best with these motors to crank steady until they fire, but not more than 90 seconds at a time, with at least a 1 minute rest in between attempts.
several 20 or so second attempts will drain a battery fast.
once the motor is spinning, there is not really much strain on it. they are designed to handle heavy loads. it's the starting and stopping and starting that will wear them out, and drain a battery...

to sum up. -40°F/C is too cold for Diesel... however, it's too cold for gasoline too, and there ain't no good way to thin a gasser's fuel to get it going...
western Idaho rarely sees -5, so I wouldn't worry too much.

I just looked the weather averages for your winters... -27°F record in 1957... THAT would be a cold morning to try to start a diesel...

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