The remaining ribs support the cargo area floor and are aft of the rear spar carry through. The first two pictures show the two step support subassemblies. These are were the external step will attach to the fuselage.  Since the step can support a very heavy person this has to be pretty strong.

All of the ribs have been clecoed or riveted in in the third picture. A cross member is having nut plates attached in the last picture. This finishes off the rear half of the fuselage kit for now.