Given the 7 1/2' dimension, a cattle panel hoop has a lot of possibilities, yes. Three panels might just make 12.5' if you have the 50" tall ones, and you could always set a raised coop as the "back wall" of the arch. Tarp or polycarbonate panel that end as a roof, leave the "front" of the coop open for ventilation, and the rest of the roof either open or perhaps a shade cloth cover. Then its just a matter of putting something on the front arch to finish enclosing the space.
Maybe upcycle some of the old metal shed, condition dependant.
Maybe upcycle some of the old metal shed, condition dependant.