Simple answer to your tanks freezing, YES
I've done deer camp in North Dakota.
First thing to freeze, will be the dump valve.
I have the electric heat pads, with enclosed underbelly and heat duct into the tank area. My warm holding tanks are useless when I can't dump.
What I have done, when hitting the road, I put disposable pocket warmers inside the dump cap. When I get back to town, the dump valve is usually thawed enough to dump.
For traps and water lines, I leave cabinet doors open, to allow heat to get under sinks, etc.
Another thing you might consider: put a gallon (or two) of RV antifreeze in black and grey tanks.
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