I have been considering three possibilities for a vehicle that could serve as an off pavement and rough road vehicle. It also would be capable of towing a 4000 lb. travel trailer for the times we want to set up camp for an extended period and stay put in a campground with amenities. I certainly would buy an EarthRoamer XV-LTS if I could afford it, but $300k is beyond my budget, so it's between these three.
The first is a Sportsmobile Ford E350 Extended Body 4x4 conversion.
The second is to take an F350 crew cab long bed/utility bed pickup and put an Alaskan Camper pop up unit on back. We would take out the rear seats and put in a very small fridge and a porta potti for use while the truck is in motion.
The third option is a Provan Bengal Tiger on an F350 long bed.
At this point in time, we prefer the layout of the Tiger and its larger size. Other than the cost, I have one overwhelming concern.
As Stephen Stewart describes here
off pavement, and especially off road vehicles suffer great torsional stresses. Vehicles built on pickups and trucks are more likely to experience flex than the Ford van as the van frame is very strong, while pickup and trucks have a frame designed to allow the cab and payload sections to flex independently of each other. This is illustrated in these pics of Jay Shapiro's F650 build:
2nd through 7th pics in this post:
2nd pic in this post (finished build-note caption re. ripped bellows):
Most pickup trucks have a separate cab and bed to allow flex between the two. Some older unibody exceptions, based on car frames, were Chevy El Camino, Cadillac Mirage, Ford Ranchero, and VW Rabbit pickup. Today's Sport Utility pickups like the Honda Ridgeline, Cadillac Escalade, Chevy Avalanche, and the crossover SUP Subaru Baja are unibody. The only true pickup that I've come across that was unibody is the '61-'63 F100. All of these were/are relatively short vehicles. Most big trucks also have separate cab and body, though U-Haul types and some other delivery trucks are fused. I think of all the Unimog type Overlanders that have completely separated cabs and cabins.
Stephen Stewart states that when using a truck chassis as a camper platform, if one wants to have a passageway between the cab and chassis, one of two solutions has to be employed to solve the problem of torsional stress. The first, which involves fusing the cab and chassis, is to greatly strengthen the frame so that it simply doesn't flex while firmly affixing the cabin to the main frame in a minimum of three non-linear points. The second is to join the cab and cabin together so that they can move independently. This is accomplished by putting the cabin on a subframe (normally two rails) and joining the cab and cabin with bellows.
Jay's EcoRoamer uses subframe and bellows. So Does EarthRoamer on the XV-LT and XV-LTS, and Global Expedition Vehicles on the UXV-550 S-84.
(Update 10-9-11: Provan is soon to release the Siberian Tiger which will use subframe and bellows. The Unicat site shows the subframe and bellows method for an XV on a F-550, in 4x4 and 6x6 versions built on all 3 cab sizes. Apparently, this is concept only at this point, as I can find no evidence they have ever built one. The copyright date at the bottom of the page is 2006. On another page they have a copyright 2007 design they released built on a Dodge Ram 5500 which they apparently never built:
There are several pickup based 4x4 Class C vehicles that I have found which fuse the cab and cabin and attempt to strengthen the frame:
The Host Super-C Series:
The Xplorer Xcursion Series:
The Provan Tiger CX and Bengal Tiger:
The Krystal Motorhomes Models 30 and 33:
The Suncamper Sherwood:
The AC Landcruiser 80:
Three discontinued 4x4 pickup based class C motorhomes (all with fused cab/cabin) that are no longer produced include:
The Serro Scotty Pioneer 4x4 and 6x6:
The Revcon Trailblazer 4x4 and 6x6:
A number of these same manufacturers also produce(ed) motorhomes based on vehicles other than 4x4 pickups. Some interesting German campers, built permanently on pickups, yet having no pass through can be found here: http://extremfahrzeuge.com/Geocar_CONDOR.187.0.html )
I have been researching the Tiger as much as I can. On the Yahoo Tiger users forum, I find very little evidence that Tiger owners take their vehicles off pavement very often, almost no record of Tigers being taken onto rough unpaved roads, and absolutely no record of going completely off road. I also find a disturbing trend of the cabin developing cracks just behind the place where the cab and cabin are fused. The owners reporting this phenomenon have no idea what the origin might be, however I fear that Stephen Stewart's observations about torsional stresses are likely the source of the problem. Here is where the problem is discussed amongst Tiger owners on the Yahoo forum.
I welcome comments and observations about these cracks in the Tigers. Do my concerns about torsional stresses seem reasonably founded? I also worry about the Tiger's suitability in withstanding stresses of harmonic resonant vibrations on washboard roads. I love the Tiger layout, however a little voice is whispering to me that the 4x4 on Tigers, Revcons, Host Super Cs, and Xplorer Xcursions is best utilized on icy paved roads, and not on unpaved rough roads. These vehicles also do not have the suspension upgrades that EarthRoamers, Global Expedition Vehicles, and Sportsmobiles have. For any Tiger owners (or owners of those other three) who have done serious off pavement/rough road overlanding, I would especially appreciate your observations. Thanks in advance.