On my ERA, I bought a sheet of aluminum at the local hardware store, and had my painter slit the back edge of the hood so we could insert the aluminum sheet between the hood inner and outer skins.
I used a "427 style" rivet-on scoop on my car, and the rivets help hold the aluminum in place. Then he glassed the back edge back together. Have to be a little careful how thick thick the aluminum sheet is...the first one I tried was a little too strong, and wanted to flatten out the normal curvature of the hood...had to go back and get a thinner sheet of aluminum.
Did the sand, fill, and smooth on the underside of the trunk - the curvarture there was way too tight to insert an aluminum panel in there.
regards,
Jeff