HOw is the area under your sail panel for rust?? After your comment about trunk pinholes and if the top had been up got me thinking.

When I did my car ( in pic) after I had it blasted on a rotisserie and primered, a body man looked at my sail panel and told me to remove it. Got out my torch and removed the lead/spot welds.. I found alot of rust ( surface) issues.. I removed most of the body/convertible pieces under the sail panel, blasted and painted them, then reinstalled..

Just a thought