better off in a disel landcruiser, although wouldnt be as much fun, its what i'd be lookin at.
no problem finding fuel, more comfortable (important on loooonnnggggg trips), and better range (long range tanks etc). not to mention you can take it to some harsher places. although sti or evo would be ok off road, for places like NT and up in WA, cruiser would be hell of a lot better, plus you dont fel as bad if u put soem scratches/dents in it
PS, you can get landcruisers with trims like winches, fridges, lots of good things.
also, trip is about seeing things, not driving a spots car, go the cruiser