Here in rural Western Australia there's a range of official vehicles, the local (wheatbelt area) farmers have supplemented them recently with an ex military unimog purchased at auction and fitted with an 8 (ish) tonne water tank (with anti slosh baffles) and extra cab insulation.

Not sure where specifically they sourced it, one of the military surplus auction houses like:

https://www.australianfrontlinemachinery.com.au/vehicles/uni...

Does the job and scrambles well.