In my experience, with everything done up right before you set off, it will almost certainly take you there and back without any problems.
I would recommend a cam belt change, new bearings all round, a proper set of tyres so you don't get stuck just about everywhere you go, and a full compliment of air and lube filters because you would need to change those out a bit more frequently than if you drove on tarmac.
You need to ensure that your cooling system is functioning at 100% because when you consider you may find yourself driving at some of highest recorded ambient temperatures through sand or muck in low gears at high engine revs, the last thing you would want to do is have to replace a head gasket in the middle of nowhere.
That said, I have always maintained that the best engine suited for this kind of endeavor is the 200tdi. Many may argue that point but its worked for me, and at 310, 000 its hardly broken a sweat.
To end, carry along an extra complement of tools (standard 6 to 32 mm socket set), a set of spanners, spare drive belts and install a winch to help out when even low range can't help.