The .016 skin wrinkles when it is pulled up to the tabs on Bulkhead C. In order to prevent the wrinkles I drilled a few holes (about 3), installed cleco's and then trimmed the .016 skin to fit the tabs as shown above. This stops the wrinkling on the bottom of Bulkhead C. The tabs will be covered when the skin is wrapped from B to C. You don't have to do this all the way around, just until the wrinkling stops. I trimmed the aluminum skin as I put the cleco's in with a Dremel cutoff tool.