You know, playing off the subject line word "Ultimate", the thing that comes to mind is a van-based camper, of sorts.
Here me out...
Conceptually speaking only (your version or interpretation may vary), I've loved the idea of a van platform with a few creature comforts/necessities on board, like any of the
Sportsmobile offerings, especially the 4x4s. But there's a whole slew of options out there, from really expensive to dirt cheap.
I grew up camping with my parents in the 70's and 80's, both in trailers and motorhomes, and as kids we used to walk around all over that motorhome while my Dad drove us to wherever we were headed. Gotta pee? Walk to the restroom in the back, but be sure to hang on to something, otherwise mom becomes a very unhappy person. Hungry? Sit at the dinette and chow down. Tired? Lie down for a nap. Good times... Not so much when towing a trailer though. Anyway, a van is just a smaller version of that.
Not trying to derail anything, since I've often thought the same thing. Just another option.