Start running Howes in your fuel NOW and don't stop. Make sure to pop a fresh filter on right before you leave and have a few spares on hand but if you start treating now you shouldn't need the spares unless you get a bad fill, but a bad fill of really watery dirty fuel in severely sub zero temps can have you changing filters every 30 miles, but if you have been running Howes the whole time, chances are you won't have any problems. I've been in -80 and worse with that stuff and come out OK .I've gelled on every other product out there at one time or another
If you are running a heavier lube in your diff, consider going to a lighter one. Make sure your door seals are tight( nothing worse than snow blowing in past your door seals) Invest in a set of snow chains there from Security Chain there in OR, some of those lightweight chains with the diamond pattern stay tight and don't break, or even better invest in a set of dedicated snow tires for winter ( no , ALL weather , all season, or M+S do not count) get some studded Nokians or Green Diamonds so you can actually drive on ice and not have to worry otherwise you are going to spend a great deal of time in the ditch looking up wondering when the wrecker is going to get there