I agree with all who warn about "optimistic" capacity and weight specs from most all manufacturers.
I do know a guy who had a F150 regular cab 2WD with the upgrade package and claimed 3,200 lb payload. He upgraded to an F250 and within a week went back to the dealer and got his F150 back.... (ride quality issues)
I don't know much about pop-ups but I have followed a full time nomadic family on YouTube for years. Much of their travel has been in an F250 with a 4 Wheel pop-up. They have traveled coast to coast and back across Canada and then down through Mexico to Guadalajara in their 4 Wheel camper (all from California). All this in 2016. His wife and 3 small children (at the time) had no problems sharing the space. The only issues I remember him mentioning in his videos was a problem with water intrusion in the front area and then normal wear and tear hardware failures. If you'd like to check out his experiences just do a YouTube search for ... Mali Mish Travel Vlogs ... and scroll down to Playlists entitled "Canada, The Great White North - 2016" and "South of the Border - 2016"
This might be a good place to start ....
Introduction to new 4 Wheel Grandby
