Just keep an eye on the forecast! This week is supposed to get cold at night (in the 20's) but I think warmer during the day. Yes, my faucets broke in Corvallis! It wasn't so much how cold it got at night, it was how cold it STAYED during the day (mid-20's).
There are two ways to do this, one is what I call "deep cold and fully winterized" and the other is "cold at night, above freezing during the day but not fully winterized" mode. In BOTH cases I like to have electric hook-ups. I boondock spring, summer and fall, but I want electric hookups in the winter. The furnace is too noisy to sleep at night and I don't want to get super cold, so we use a space heater.
Deep cold and fully winterized ("pink stuff" in the macerator, traps, and in the water lines, -empty fresh water tank)
Yes, you carrying your drinking water (we have a 2.5 gallon jug we keep in the shower, plus a gallon container in the fridge) we use for drinking and light cooking. No heavy duty cooking! Just heat and serve stuff. We flush the toilet with our antifreeze. No showers in the RV but we normally park at nice RV parks with electric hook ups and park our RV close to the bathrooms, so we can shower, etc. using our "shower basket" (a little basket with shower shoes, towel, soap/shampoo, etc). We use paper plates, etc. to keep the washing down. I also have an old laundry jug (the kind with a little spigot) filled with water for washing hands and maybe a pot or two. It has another 2.5 gallons or so of washing water that we also keep stored in the shower, but it can rest on the counter with the spigot over the sink. So I don't use ANY water from the now empty fresh water tank if it is going to get and keep cold (below freezing) and I have fully winterized. Lastly I keep another jug or two of anti-freeze and I toss a cup of anti-freeze down the drain for every 2-3 cups of water that goes down the drain. Most RV non-toxic antifreeze is good to -50 degrees, so it will keep things from freezing in 20 degree weather even if it is a bit diluted. I keep non-slip shelf liner in the bottom of my shower to keep the jugs from slipping and sliding.
Cold at night, above freezing during the day, not fully winterized.
We have water in the fresh water tank, we have pink stuff in the macerator, and we blow the lines out after dinner every day. You can still use all the water functions during the day (although we may still use the RV park showers) and we still make sure that we back-fill the macerator with pink stuff after we dump our waste tanks. We are still stingy with the water use so it won't cause any problems.
We also have "heating pads" on our tanks (it was a special order add to our Unity). We can also keep water in the fresh water tank from freezing if night-time temps dip down in the 20's IF WE ARE HOOKED UP TO SHORE POWER. It doesn't work otherwise. We only use this if the daytime temps will go up above freezing during the day. So what we do is we can use the water during the day and up until dinner, then (most days) dump the black and gray tanks, make sure the macerator has "pink stuff" and then we blow out the lines and keep the heating pad "on" for the fresh water. The inside of the rig is kept warm with both the furnace and a small, silent, oil filled space heater. We also remove the shower head of the outside shower and stow in our house. We keep the cabinets open or pour a little pink stuff in the traps. For night-time flushes we use more anti-freeze.
I also use lots of reflectix on the windows, and a big, thin blanket to form a "shield" between the front cab and the house, as the cab is significantly colder (and less insulated) than the house. It really helps! Yeah, we are trying to use a 3 season rig to work 4 seasons. Wish the Unity was a true 4 season rig.
Hope that helps. If anyone else has ideas, chime in!