If you want to go feral in the bush or the desert, start with a fair dinkum 4WD wagon or one-tonner ute, priced from about $35,000.
Make it outback fit with all-terrain tyres, off-road suspension, bull bar, roof racks and snorkel. Put a canopy on the ute or a cargo barrier in the wagon.
Install a deep cycle battery setup to run your fridge and lights. Fit an awning for shelter. Budget about $20,000 for the fitout. Buy quality gear from ARB or another reputable brand. The cheap stuff will break.
Complete your adventure truck with a few jerry cans, gas stove, comfortable folding chairs, table, tent, swag and camp stretcher to keep you off the ground, dry and safe from the snakes.