In the conditions you describe, the most common source of freezing is only your supply line. In those situations a person leaves the water running a trickle to prevent freezing in the hose and spigot. But this is NOT your situation.
Your situation is while in storage and not connected to any utilities.
I definitely would not winterize with antifreeze.
But being a compulsive person myself, I do think I would drain out all of the fresh water using the low point valves and the fresh water tank drain.
That should take care of the lines. Even if there is a little water left in the fresh water tank it will not matter because there is all kinds of room in there for the ice to expand harmlessly.