Consider whether or not you *need* water. Are there showers available at work?
We've been doing winter camping for the past 10+ years... It's entirely possible to limit your water use without needing to keep the trailer above freezing temps all the time.
- We bring 5 gallon water bottles for our drinking and coffee water, and found a $10 water pump that seats on the fill tube for dispensing
- For the toilet, we have 1 gallon jugs of flushing water
- Hot water for washing dishes gets warmed up on the stove
- We use Rubbermaid dishpans to contain our wash water, and can either drain that into the tanks or disperse it outdoors if that's allowed
- If showering isn't available, you can use stovetop warmed water and a washcloth to manage the "essentials" (I keep my hair USMC short, but you could probably manage to wash your hair in the sink this way)
That approach has worked great for short 1-2 night trips where showers are optional or available at the destination.
This year, we didn't need to dump either our black or grey tank between November and March after seven days of use. But... we have 40 gallon black tank and 60 gallons of grey. Smaller tanks might present a different issue.
Frozen black tanks aren't as much of a problem with low usage as you'd think. Gallons of water in a large tank take a lot longer to freeze than what you get in a cross-section of pipe, and the ice contains odor quite nicely...
- 2019 Grand Design 29TBS (had a Winnebago and 3x Jayco owner)
- 2016 F-150 3.5L MaxTow (had Ram 2500 CTD, Dodge Durango)
- 130W solar and 2005 Honda EU2000i twins that just won't quit