I needed to trim the bottoms of the fairings to clear the brake arms, so I installed them, marked them, removed them, cut them, and finished the edges.
I was also having trouble aligning the hinge halves to get the pins in, so I drilled a single hole at the center of the fairings, from front to back. Now I can put in a bronze cleco to align them, and put the hinge pins in place without too much difficulty.