I regularity tow with the tank about 1/4 full when headed to a campsite. Never had a problem.
Most of the time heading camping, I have a full tank and just tow back what I don't use to be topped up later.
For me, the fresh water tank level is not a concern.
2017 Escape 5.0 TA (someday soon, I hope
2015 Ford F150 Lariat 3.5L EcoBoost
2009 Escape 19 (previous)
“Most folks are about as happy as they make up their minds to be.” — Abraham Lincoln