I suggest you look for a used older forest service SUV, they typically used full time 4FD Dodge Ramchargers.
Mine had a 360 V8, a tourque flight auto trans, and a NP203 full time transfer case, and a limited slip rear axle. Add some really good sized tires (12.5 x 33 in) and they can go anywhere. Who cares about scratched and dents cause you have only spent 3-4K.
Be prepared for major servicing and repair, the USFS really uses them before selling them. But once they run right they will go anywhere.