Don't you just love the bodges people used on these poor SC's. I had exactly the same thing in my Chief, drywall screws holding down a second waterlogged layer of plywood under soaked carpet. I should have weighed the wood I took out. I found that if some care is taken to make sure you don't bend the underlying aluminum, you may be able to tear the over decking right out using a prybar around what ever screws you can not get out, pulling the screws through the wood or out of the under decking. This also worked for me for portions of the original 1/2 " deck and the original rivets were left in the ribs to be taken care of later, though they can be drilled out easily. Yours may not be that far gone, or if things have dried out this would not be as easy as if it was soaked like mine was. This destroys some deck as a pattern, but it should not be too hard to remeasure and layout the replacements.
Ron
:laugh: We got a pry bar under one joint then forced the 2x4 underneath. Started whacking the board till the deck finally came free. It wasn't easy. And still had to go back and remove the screws from everything afterwards.
