It would be a really nice feature to have Sketchup manage the accuracy problem by automatically scaling up the geometry so you don't have to worry about it. Enter and display dimensions as usual but behind the scenes it's all scaled up by 100x.
I've made some progress. I learned how to import a real airfoil with a non-zero thickness trailing edge (NACA 0006) and loft it into a simple fin shape. Then I used the technique in the video to make a fillet. It's pretty good and I'm going to close this thread. Thanks for the help cotty!