If it is necessary that you make the trip then I would grab a couple gallons of RV antifreeze to flush the toilet and a standalone heater like a little or big Buddy for emergency back-up.
Add some extra food, water and blankets in case of emergency. Keep your fuel tank and propane topped up as often as you can.
If the weather is crazy cold try and stop around fuel stops/people in case you have problems at night so you are around others.
I would only run heat during the day if you know that the TCer is air tight. No sense heating air that is being replaced by cold air all you are doing is wasting propane. Do stop 15 - 20 minutes before you are stopping for the night and turn up the heat and if you can get a 12v heater for the bed. It will at least take the bite off. If you do not have two group 31 batteries for the camper then it may not make it through the night running the heat.
Once you get where it is warmer then I would drain the waste tank and add water. This winter is suppose to be like a yo yo for temps
This will take you to a PDF of some tips for winter camping in extreme temps.