Welcome to ExPo. You'll find lots of ideas and opinions here.
Expedition camping falls in several categories
-- modify a standard vehicle to include a sleeping platform inside (unlikely to work for more than two people)
-- sleeping in a tent beside or on top of the vehicle, with gear carried in the vehicle
-- pull a camping trailer (lots of options here)
-- mount a camper onto the vehicle (this includes slide-in campers for pickup truck, and custom campers mounted to a larger truck's chassis)
You'll find plenty of examples of these approaches on ExPo.
Three additional questions to guide your selection
-- How much do your wife and daughter like rough and ready camping?
-- What sorts of off-pavement driving do you want to do? (travel on forest service roads? overcome small obstacles? unstoppable rockhopper?)
-- Will the vehicle be used as a daily driver as well as for recreation?
You don't need a super-specialized vehicle for adventure travel. People have traveled around the world in ordinary sedans. A vehicle modified for off-pavement travel will let you choose a wider range of routes, which will lead to different sorts of adventures. It's all good. The important thing is to get out there. Your experiences will tell you what sorts of additional gear you want to buy.