Custom rear fuselage access port reinforcement

Like with the wings, I fabricated a reinforcing surround for the rear fuselage bottom skin, from 1mm 6061-T6. This provides a more substantial amount of material for the rivnut to clamp on to. The rivnuts holes were reamed to 6.1mm, secured with JB-Weld. Spots of Sikeflex 291 were also applied. Note the aperture is slightly smaller than the hole cut in the skin, in part to overcome the very small hole-edge distance. The aperture has the same size as for the wings.