Finally! I got started on riveting the main skins to the skeleton. It took a bit of fiddling and shifting of the counterbalance skin to get all the rivets to sit flush, but I eventually got all the rivets in the top of the rudder set, including the R-903 tip rib, except for the aftmost two on each side which will require the indirect backriveting technique demonstrated by EAA's Wally Anderson in this video: http://www.eaavideo.org/video.aspx?v=5337092001
Tomorrow's another workday (at the job that pays for the project ;O) )so that's it for tonight.