Better to have a static system, if you have the Ro in van , you will need one that will produce the water you need over night , then you've also got the van tied up over night, all I have in van is pump, varistream , battery , 500 ltr tank ,
Have a 200gpd Ro filling a 1000 ltr ibc container , have never run out of water , and even turn it of for a few days, also I can part fill my van tank if needed , where as if it's van , you will always have to carry a full tank of water
Daz