regarding expensive overland rigs...i have seen a lot of them on the road and that is where they stay, on the pavement. The problem is the weight; as soon as they are driven into soft off road conditions, they sink, are stuck and only a bull dozer can pull them out. The 4x4 capabilities of these rigs is completely useless. If a road, route, piste is hard enough to not sink in, then even a standard motorhome can drive on it. I have seen the entire range of vehicles travelling around south america (bermach, Unimog, MAN, Fiat Ducato, LandCruiser, Defender, regular large motorhomes, Citroen 2V, Mazda pickups, etc.) Almost everyone of these vehicles must stay and does stay on pavement roads. The only vehicles which are capable of going "in the jungle" or wherever else the road is full of sinkholes are light vehicles like Defenders, Toyota Hilux or pickups. Even the mighty landcruiser is a little too heavy for some of these conditions (i have pulled out many a landcruiser with my Defender). So the decision to buy a big rig or not depends on if you want to leave the pavement or not. And when you leave the pavement, it is inevitable that you will hit a soft patch at some point. So stay on the pavement and you can drive anything you want including the longest 2wd motorhomes. Go off the pavement and you will be wishing that you had bought a light vehicle instead. Another point to remember is that the more outlandish your vehicle is (MAN or whatever), the higher chance of robberies. You look like you have money. I drive around in a old defender that looks worse than most of the local vehicles, even though under the skin it is a new machine. I have never been robbed or had any problems. another thing to think about is water: when you have a large machine with 500L or more fresh water capacity, no one will let you fill up the tank at their campground, service station or whatever. Water costs money and you are taking way too much. furthermore, with a large rig it is impossible to enter towns or cities and you must find secure parking outside of the town; lots of fun when you need to find someone to change your oil, or you want to buy food, or someone to wash your dirty clothes...Lastly, i have seen many big rigs stranded for months waiting for some special part to be shipped in from Germany or wherever. It may just be a little thing, but it doesn't matter as every single part on the machine is unavailable locally. You had better have very good local language skills, patience, lots of cash money for bribes and import fees.
a little story for you: i was driving on a small hard packed but unpaved road in south america. As is very common, it was very narrow most of time (one vehicle) and it was very isolated with no places to turn around or branch off onto another road. along the road i met a MAN driven by rich guy trying to 'test' his machine....i told him what a beautiful machine he had, but i never bothered to tell him that 100kms ahead was a hand cut tunnel that was less than 2 yards wide and 2.5 yards tall. I never bothered to tell him because it is the kind of information that is not at top of mind for me - i simply didn't realize it at the time that he could not go there.