I am still working on getting ready to add both aft skins.
I riveted all of the gussets on using both the squeezer and rivet gun to work all the access situations.
I marked the center lines on both j-stringers and taped them in place. I am a little concerned about the j-stringer lengths. The skins are what set that length and the j-stringers are just "floating" until they are match drilled to the skins.