Just two points. One buy some starting fluid. You may need it for the genset and or the cummins. But use it carefully. Often a small squirt will do it.

Second make sure you hot water heater is drained. Was kinda inbaressing when I got down south and the tank had burst.

Put anti-gel in your fuel tank during your last fill up before parking it. It should get circulated to the engine before shutting it down.

I used to leave MN when we had a bus (GM PD4106) and often it was in the teens below zero. Worst was 25 below. Never had a fuel problem with the Detroit as they really could heat up the fuel. But the propane genset ran until I reached warm weather. Had the propane furnace running plus two electric space heaters and the engine heat. Wore a snow mobile suit, boots and gloves. Biggest problem was shifting the 4 speed spicer for the first few miles.

some states got real good 800 numbers and internet sites for road conditions, my favorite one is wyoroads.info for Wyoming. includes pictures, closures, weather/wind etc
Keep fuel tanks full, do not go below 1/2 tank.

And if you go to the DOT websites for Oregon and Wa. they have traffic cameras for some of the mountain passes.

Make sure you have a working carbon monoxide detector (in addition to LPG and smoke). Everybody should have one.
On a lighter side: I think the History Channel is looking for some participants for their new series "Ice Road Campers"

Have you been watching Ice Road Truckers, Deadliest Roads?

yes, we both like it and watch it whenever possible. Missed last Sundays Himalaya. I would not drive overthere! It's like bumper cars gone wild. Not to mention the donkey path they call highway. Makes the ice road look like the autobahn.

They have been showing repeats of the episodes several times during the week. In fact they are showing the first one right now and will be showing the others right after. Newest one will be on later tonite.