I did see your inquiry when you first posted, and I'm really having trouble understanding what it is you seek. I cannot imagine any condition when you would run heated air via ducting either around or through waste storage tanks. The existing method is to add an insulated heating pad on the bottom of the tank, and only the bottom at that. I am unaware of any conditions where this method is inadequate.
Of course, the fresh water tank is inside the heated coach, so freezing isn't an issue for it.
I do recommend the double-glazed coach glass; great for the cold weather.
2019 Minnie Winnie 22M on an E-450 frame