Something to consider for your replacement camper build is a water recycling system. It could save 500 pounds or so. You basically have two small tanks, one about 4-6 gallons (holding tank for water to be filtered) and one about 10-15 gallons (fresh water waiting to be used). Multiple levels of filtration, down to sub-micron level, if desired, take gray water and re-condition it back to potable water standards. This is assisted by using non-toxic cleaners, soaps, shampoos, etc. You can also incorporate UV light, reverse osmosis and the like, if desired, but realise that you are only removing what you put it. So, if you start with clean water from the tap or a known good source and take a shower, there is no need to design a system to filter out polio, giardia, heavy metals and pesticides, as those cannot exist in your closed loop system.
It allows you to carry much less water on the truck and to wash as many dishes and take as many showers as you need. Both, a huge advantage, especially when boon docking or in a remote area, where services may not be readily available.