6'-7', 320 lbs. I have a Strongback Elite chair that is decently strong, and folds up well, though I find it a bit uncomfortable under my thighs.
Quite simply the most comfortable and ergonomically healthy portable chair on the market. You will inmediately feel the difference in comfort and back support.
www.strongbackchair.com
My preferred chair if I have the room in the vehicle is a fold flat camp chair similar to this:
Mine is from Coleman, the one above is from Costco, there are many variations. The Coleman one I have has less plastic. It has served me well for years.