That's how I did it. Just finished it up the coaming over the weekend. I think fiberglassing in that order allows for the easiest transistions. The hardest part, I found, was to lay the fiberglass from inside the vertical part to up and over the coaming lip. And I used bias cut cloth.

For the vertical part go with the hot glue trick, that worked very well for me.

Ross, I really like your internal bungees for the hatches and plan on doing something very similar on my Guillemot, any leakage?