While I was working on the How-To articles on replacing the rear bulbs, I discovered a problem.  The reverse light assembly and tail/turn/stop light assembly is held on with wing nuts.  The bases of the studs that the wing nuts are attached have an edge to them.  The pressure that holds the assembies to the car causes the bases of these studs to cut into the paint beneth them.

This is a close up of the reverse light assembly and the trunk lid area behind it.  The white, round ring in the black paint in the background is not paint.  That's where the bases cut into the paint.  I don't know why Chevy didn't put a plastic washer or something else back there to protect the paint.
Here is a close up of the driver's side tail/stop/turn signal lamp assembly.  As you can see, the damaged area of the paint is rusting.
Here is the back of the stud that the wing nut threads on to.  You can see the rust stains on this piece also.

Ok, so what to do?  You cannot install a washer, because that would push both assemblies away from the car and introduce even more water.  I am thinking of getting some of that Scotch-Cal product and applying it back there.