Using hoop houses in the summer? [View all]

My SO as it in his head that the reason the tomatoes have never done well in our garden is that they get too hot in the dead of summer, and also have had blossoms blown off by storms in past years. So he got this opaque white plastic to put over the bed (on a frame) because we met a guy last year who had great tomato success with a homemade hoop house. While this will definitely cut down on wind damage, everything I've read about hoop houses suggest they might need some kind of shade cover during really hot days, and a boatload of ventilation. The hoop house we saw that gave him the idea was in an area with some natural shade; that is NOT the state of our yard. Case in point today, it's about 80 degrees out right now but under that plastic it's over 90. Isn't that going to kill our plants on hot days? Anyone else have any experience using hoop houses with plastic sheeting?