I agree.
Berchman has the right idea. I made a long post on this subject some time ago, but short story is. Get the end ribs to match the curve of the door opening, very well. Then fit and rivet them to the outer door skin and make sure that all fits very nicely in place. Once you have this done put it on, fit it very carefully, then tape it all down so it will not move, then use some straps over that to hold it in place and to the correct curve. Then get inside and carefully put the pop rivets in one at a time and start at the top and rotate one on the right one on the left, one on the right one on the left, back and forth from side to side tell you get them all in. Try not to flex anything as you put the pop rivets in as once you have them in the shape of the door is set. If you don't like it after you put the pop rivets in, just drill them back out and reset it back in place, then reinstall some new pop rivets. The thing will not be ridged tell you set the pop rivets in the bottom skin, so go slow and set them carefully. Hope this helps. Yours, R.E.A. III #80888