The M934A2 is attractive for the real-estate and price (and not limited to), but it may not be as mobile in the rough country as I need it to be. You make a great point about getting stuck. That will be a problem not having a recovery method. Maybe jacks and blocks would help in some cases.
In the summer to escape the heat I need to be at the 9,000+ Ft. level and at that elevation climb out of the graded dirt road up and over the berm that has developed over time from grading the road. There is something about maxing out the rated payload with the van/expandable unit before adding any of my gear and supplies into it. I may be asking a bit too much.
The idea of reducing the weight by removing the expandable pieces is interesting. I'm guessing that would lighten the load by ~2,000 lbs.
There are some good ideas here in this thread. I've excluded the Humvee (price) and the FMTV (not reliable enough). Its almost like the tractor and add-on box would be as off-road capable as the Humvee ambulance (or high payload truck + box). The torque bias diffs in the Humvee look pretty hard to beat. There would be more camper space in the 5-ton and cost at least 1/2 as much.
Those dirt berms are what, about 2ft high? Wouldn't be worried about getting over them with any of the setups. The truck is more offroad capable than you will be initially comfortable with.
Mostly have to figure out how much space do you want/need, does it need to be indoors, and are you willing to setup a base camp or should it all be ready to go? How difficult of trails do you want to take the truck on and what type of terrain (heavily wooded, rocks, deep mud....).
Assuming that your terrain is similar to the mountains in Utah (rock/dirt trails, no deep mud or heavily wooded areas like the southeast) I wouldn't go bigger than a m934 or the m931 tractor with the shelter on it and a m105 in tow.
Some pics of the more flat terrain out here
http://www.steelsoldiers.com/showthread.php?161052-Utah-offroad-trip-to-5-mile-pass I wouldn't hesitate to take a m934 with a m105 in tow down those trails but would not consider a longer trailer due to the tight turns.