Great answers, and very helpful. Except that there's no glaringly obvious solution at this moment in EV-olution.
I want a Tesla for the long highway portions of the trips, for the autopilot and for all the other reasons I want a Tesla.
I want a jeep wrangler or a pickup for the bad road/dispersed camping portion.
I can only get one.
I guess I could compromise on a Honda CRV - which would make nobody happy...not the anti-ICE me, not the want autopilot me, not the 'wonder what's up here, maybe a nice spot to camp, oooh, what deep ruts, well I'll keep going a few miles, no that was a bad idea' me. And it's not cheap. Spending that much on something I don't really want...
Whoever comes up with a portable solar supercharger will rule the world.
While not an ideal solution, how about bringing along a portable generator for when you're totally off road? I have a Champion dual fuel generator at my cabin that runs on propane. You could probably use the generator for other things while camping, and the propane as well, and top off the Tesla as well.
I have a generator similar to this one and it's not bad on propane and not that heavy. It'll take up a big chunk of space in the vehicle, but if the video is even close to accurate you could get more than enough range out of a 40 lb propane tank to be comfortable off road.