Woohoo, sanding the dowels wasn't that bad. I used a different method than Chris did. I have not doubt that my dowels have some flattened spots but I'm sure they are close enough! I laid them on my cabinet door/sawhorse workbench and sanded as I rolled them slowly along. I sanded about 60% of the dowel at a time with sweeps towards the end. Then you flip them end-to-end and repeat. I snagged the tip of the second one and pulled a small sliver off, so this became one of the thinner ones. All-and-all, not too bad...and no cussing.
Meanwhile, the fins are being installed. I added tick marks on the inside of the body tube in-line with the fin alignment lines. When this is centered on the fat part of the fin and the pointy end is right on the mark, you have perfect alignment.
The tower is built and the three balsa cones/transitions are being sealed with Fill'n'Finish.