While I'm nowhere near thinking of a change, the one thing that I've found to be a problem that I simply never considered was being able to build out the truck to serve my purposes without going over weight ratings.
At this point I've kind of accepted it as a necessary tradeoff and also acknowledge that it's a lot to ask of an already beefy vehicle to simultaneously be an occasional daily driver, extended backcountry camping rig (i.e. lots of water, fuel, tools, self-sufficient stuff), and to safely negotiate relatively technical trails (Hells in Moab, Slickrock in Sierras, etc.).
This, whatever vehicle you build up, short of a military based 4x4 transport, is going to end up near its weight limits once you turn it into an expedition vehicle. Camping conversions are heavy once you start adding options. Then add the usual self-sufficient stuff, body armor, winch, jack, etc. etc. My Sportsmobile was about 1-2K over the GVWR of the E350 chassis. The guy who bought it from me spent a couple of years getting the suspension worked out to handle the additional weight sanely.
Water and diesel add up fast. I'm carrying 80 gallons of water at 668lbs and 75 gallons of diesel at 525 lbs. That puts me at or just over the 13K GVWR of my current fullsize 1-ton 3500 pickup when fully geared up for a long trip. For weekend trips I only fill up 1/2 way to try to keep things sane.
I'm finding myself shopping more and more for camping gear in the backpacking section...