Interesting thread. Following, as Ive been struggling to find a solution to something very similar to your situation Zybane as I am in a very similar situation as yourself.
Since your considering military chassis, is there a reason you have not listed a 5-ton as a possibility? I have recently considered that turning my OBS ford into a nice comfortable expedition rig that is full-time live in capable would well exceed the max weights, and make it less capable off road even if weights was not an issue.
I'm curious if you could expand on your requirements specifically pertaining to off road capability. I find different people have very different definitions on what is off road, what is 'easy' off road, and what is not even passable (as found by a coworker even just yesterday). I ask because as many of the previous discussions seem to point out that less is sometimes more, and like you I also find myself constantly wanting to go bigger, but that doesn't necessarily mean better (especially if something breaks a long way from a service center or even highway). I think the biggest issue maybe is that for a good comfortable set up, and to be able to be somewhat off road, that a big truck is needed just simply due to weight? However, In my experience (and I travel off road every single day for many miles in areas where you wouldn't see another person for days - all for work haha) these big trucks would never make such roads (I'll try and get some pics today), and many of which have some significant off-camber situations in the worst places. Usually such roads absolutely require a dozer to rebuild them prior to any sort of 10K plus vehicle to travel them. And so it is more likely that such a nice truck would really be needed only for things such as ice/snow, bad roads, the occasional good quality forest service road. In other words, only traveling to front country places and established campgrounds, and that a ATV of some sort would be needed for deeper explorations. In a way, it almost makes it so that a trailer would suffice, even though we both probably don't want a trailer any longer (I have full-timed for 2 years as well in a 21' springdale).
Just some thoughts I consider for myself anyway, and so am curious to hear what you (and the community) think are the realities as far as 'off-road' capable means with a vehicle that is so big, heavy, and top-heavy.