Lots of progress this weekend. I was able to glue all of the gusset strips in place, then (once dry), removed all the staples and sanded the fin and rudder to their final shapes. Now it looks like an airplane part!
Update: CAUTION!!! Don't do this yet! The rudder horn goes behind the spar (not in front), so the bottom of the rudder that I just covered up with plywood now won't allow me access to the area behind the spar to attach the rudder horn. It looks like I'll have to cut an access hole or something.
Total Time: 12.0 hrs.