Not a single mention of recirculating showers? In the van-curious phase of my life I have watched and read about several such setups and, albeit a bit gross, it certainly beats showering once a week? Of course if shower stalls are shared among many people, you'd have to bring your own filter (and cleaning your filter takes, well, water, but I assume relatively little of it), but it sounds at least doable and worth the quality of life improvement?