Much more refining yet to do, but I got the hinges mounted on the flat copper pipe that uses existing screws in the wheel well lip. Need to drill one more screw hole in the forward part, but I can do that in the plastic bumper, so no rust issues there.
Need to trim the copper, and I may replace it with stainless if I don't think it's sturdy enough with the full weight of the completed frame & skirt:
Below: side view. The frame is just tacked together at this point. Going to add some triangulation for strength.
Below: view from above... There's about a 1 inch gap between the tire/hub cap and the frame. Accomodates 1/4 turn of the steering wheel before contact.
Front view:
