I am 6'5" and 250 lbs. The truck camper works for me fine. I would hit my head on the A/C unit if I stood full height under it but it doesn't bother me. Some campers didn't have the interior height so I avoided them. The U-shaped dinette works fine in my model because it has enough room at each end for me to sit. It is better when the table is absent. I would like to replace it with one of those adjustable tables.
All truck campers that I can afford or have the ability to carry are tight on space. I buy it to sleep and cook in, not "hang out." I prefer to sit outside if at all possible, so interior room is not that important to me. If I had bought it to live in I would buy another type of motorhome. Having the ability to park nearly everywhere, tow something and to fit in nearly any campsite are worth putting up with a small interior.
Good luck with your mission.