If all you ever do is go from FHU site to FHU site in good weather and well known roads then traveling without water onboard is not that bad.
That is not what we do. At departure, the potable is full, the black is empty and we will be a full fuel before the end of the first hundred miles.
Between October and April, we will always be provisioned for three days. We have often been held up for a day for weather in the off season. On one memorable occasion, that became two days. So, we sat in the parking lot in the nice warm coach and watch other people struggle to get somewhere.
We have often been held up for weather or road issues and the places we go often only barely have GPS coverage. If we could not run completely self-contained, it would be a sincere cramp for our style of traveling.
Matt