Bob, who purchased my instrument #2, came over to give me a hand. He handed me clamps and helped align the rib garland. Because the open time of hide glue is so short, another set of hands is critical for this task. The alignment isn't perfect, but I was able to adjust things a bit after the glue had partially set.
Gluing the cleats and bass bar was much simpler.
I also showed Bob how I measure the vibration modes using Audacity and an old Thinkpad. The back's mode 3 and 5 are both "C", an octave apart. I'm guessing that this instument will be strong in the lower end, perhaps at the expense of a bright high end.