Decided to also add doublers just aft of the landing gear box. This areaonly had a 1mm plywood perimeter as shown in one of the photos.It may not really need any other reinforcement but I felt that with the balsa sheeting only 3mm thick in this area, a bit more balsa is likely warranted.

Added 3mm doublers as shown, recessing the edgesto sit flush againstthe 1mm plywood perimeter frame. Recessing was simple with a sanding block. I probably used more gorilla glue than necessary as shownby the foamed glue around the edges of the doubler