[Richard and Rhonda]

This is a matter of opinion. Don't start the main engine just to idle until it gets warm. The diesel won't come up to operating temp just idling, and cranking only puts water vapor in the crankcase that doesn't evaporate until the engine comes up to temp. That's one way of looking at it.

I am assuming the keeping it plugged in will keep the batteries charged. Either keep the merge switch on, or use a trickle charger on the chassis batteries. A discharged battery will freeze.