Having done the off-grid thing, shelter and power are easy - sanitation and plumbing is where it all turns into an almighty pain in the ass - and having neither sanitation nor plumbing this isn’t a “complete” solution unless part of your camping plan is “having violent diarrhoea in the bushes”.

You’d actually be amazed at what you can ram into less than a cubic meter. I’m working on a horse box conversion at the moment, and am using a cisternless toilet and a detachable worm tank to have a mobile toilet - drinking water and shower/basin water is trivial with cartridge filters, a pump, and RO. Shower is outdoor, heated, rainfall. Basin is for washing dishes and food, also outdoor. Total cost under €1,000 for a full sanitary suite. Grey water just goes on the ground, or into a tub for further use if desired, black water is stored for discharge - although the volume ends up very low due to the worm tank and waste separation.

Very solvable problems that they seem to have entirely ignored.