That's why I made my high tunnel have vertical sidewalls:
My hoops have a very shallow curve. It was easy to do, and took virtually zero skill. I didn't crumble any tubing; I don't think I came close, because I didn't bend it very much.
Top rail is ridiculously thin. The only thing thinner are the sleeve clamps that connect two unswagged ends. Those things are like aluminum foil. I learned that after 10" of ice smashed the tunnel in the picture, and I had to put it back together.