I have a ac unit on top of ours and yes it is worth the extra money you would spend. You can hang meat in ours. We usually keep it on its lowest setting.
Problem with popups that I don't like is during the winter with the heat running and the condensation that builds up. Nothing like drops of cold water hitting you in the face while you sleep.
Thanks for the info on AC units on a popup. We had a 23' trailer we used to camp in. It was well insulated and the AC would freeze you in the hottest weather. But my wife had to sell the trailer while I was in the hospital to help with bills. We are now looking at used popups.