You expressed concern about not baking your plants and ensuring adequate ventilation. Mounting the plastic on the hoops is going to increase temperature and decrease ventilation. A low tunnel doesn't provide much room for natural airflow and/or mounting a fan so I suggested a structure that keeps it more open and provides more room for natural ventilation.
Most folks who haven't tried it don't realize how hot it can get in a tunnel/hoophouse/greenhouse. Even with lots of venting my fullsize hoophouse can easily get to >130° if I pull the fans and shadecloth. Those temperatures are too high for gardening.
