Do I need to run the furnace?

[Spower]

Hi All,
I am currently in Colorado helping out in a state park so I camp for free. I am going to spend the winter here. Predictions say it will be very cold.
I will have full hookups including a heated water hose.
My fresh tank is empty (and will stay empty).
My under belly is sealed and insulated. It is heated by the furnace.
I usually pore anti freeze in the grey and black tanks while I am using it anyway.
As many have stated, I hate using the furnace due to the amount of propane it uses and really mostly because of the noise!!
The diagram below shows my cold plumbing (hot is the same). The red circle is where there is a drawer in the bedroom that I will remove and place a small space heater in there that will help keep pipes warmer (I believe).
I have other heaters and a fireplace I can use inside besides the furnace.

Soooo my question is if I add more anti freeze to tanks (not sure how much) can I get away from having to use the furnace just to heat the tanks? Or is there something else I can do?

Adding tanks heaters would be a tough job don't really want to go that route.

[GHen]

Another idea on water lines. When going to various ski resorts I always had problems with small areas of water lines freezing. Most of these areas were small channels where the water line ran from one area to the next. I used a fish tape to pull heat tape (looks like an extension cord, but heats up.) through those channels and would either leave them plugged in if I had shore power or plug them in when I ran the gen in the mornings.
Also added heat tape around the tank valves to thaw them when it was time to dump the tanks.

An old hair dryer works great to force heated are into problem areas.

I also installed a vented catalytic heater in the main living area, lots of heat and no fan noise and saved lots of battery power. Of course that does not resolve the issue of keeping tanks thawed.