Sounds like a hell of an adventure ahead. Are you planning on living in this vehicle during the excursions or just as a support unit? In this same genre I would definitely lump a 4Runner, obviously be aware of the issues with the frame when shopping around but good examples can definitely be found in that price range and they are some of the most off road capable reliable rides you can find.
Other than the cancer of frame rot that is taking my 98 4Runner SR5 to its grave the thing has gone through hell and back and been an incredible machine. Seats are very comfortable for long drives, easy to sleep in if need be, plenty of cargo room, and you would be hard pressed to find something that will handle the mud/rocks/whatever of trails better.
Good for you for getting out there and experiencing life!