I'd consider an old H1 converted to run on Diesel or Bio-Diesel. Yeah, they're way too big for a lot of trails, I've heard different reports as to their reliability, they are under-horse-powered but torque is good, expensive to work on and they are noisy. But, you go bio-diesel and you can give the finger to a city's worth of dead-head gripers.
It's got, except for size, outstanding off-road capability depending on options -- inboard brakes, 4 wheel indy suspension yet 16inches of ground clearance, tire inflation/deflation, 35s (?) standard, snorkel/exhaust for water are not problem, decent low range gearing.
Would prefer an Alpha with the better, though still not great horsepower, but those are too expensive I think in this case. And yeah I'd prefer the H1 was about 2/3 the size. But maybe an external cage (?) would keep the body intact when you tried squeezing your way through some s-turns.
Otherwise, I might do an old 70s era Bronco or maybe an old FJ or maybe even a LR Defender