Finished the second rear spar. Made sure to leave a couple of rivet out on parts 7, 3 and 5 (Page 3) so I can rivet the skin support after installing the ribs. Attached pictures are from the right spar showing the rivets that will interfere.
I also built rib 1 assembly (WG-RIB-001-R-F-2 and WG-RIB-001-L-F-2). Fairly easy assembly to build.