I agree that many pop-up won't handle much extra weight when raising the roof. However, I have camped in pop-ups for 25 years and never had a problem with leaking. A friend had one of the hard side pop-ups with fiberglass sides. They sold it after a couple years because the walls would sweat so badly. Bad enough that their blankets and pillows would be wet in the mornings. These problems might not be an issue if you leave some windows open for ventilation, or if you can keep the occupants from breathing.
Jack