The center fuselage is a bit of a 3D puzzle. You need to cleco as far ahead as possible to see in which order parts can be riveted without interference. The KAI is not very helpful in this regard.
The main spar carry through has an aluminum spacer of the exact size of the main spar. The stainless steel rivets for the main spar carry through are dipped in CoreBan23 before riveting for corrosion protection.
After waiting 4 weeks on a new u-channel for the center fuselage floor, I could install the floor skin and continue with the rudder pedals.
The directional antenna for the Lynx NGT-9000 is quite big, so I mounted it on the center fuselage just behind the gear channel. The doubler plate is made from the wing jig. That’s why the oval hole is not centered (used to be the handle hole).
From some factory photos you can see that most of the rivets in the landing gear channel are installed from the inside of the gear channel to avoid interference with the landing gear. The KAI shows the rivets to be installed from the outside.