As always it's better to be safe then sorry, but...
Your MH more then likely has a heated basement where all the furnace ducts are ran along with the water lines. Your MH will also keep your coach batteries charged as you're driving. There will be constant movement in your tanks stopping any freezing from occurring. Sewer lines are empty, they just carry waste away. You're going from highs of 30's and lows of teens to 70's so it's just going to keep getting better with every mile.
On our way north in the spring we would always hit a point in IA where we had to make a run for it. we'd turned on the furnace, and never had a problem with freezing lines in our MH.
