The post has gone way off topic (but I'm sure an administrator will soon jiggle the posts around and start a new thread)

My two pennith worth it would be easier to do 2 separate nostrils, just because I am sure every bonnet will have changed shape slightly over time and the dip in the middle will be different on each one. Individual nostrils with an inch around the edge would be easier to work with and make conform. Its not a difficult job, but then I love fibreglass you can get it to do just about anything and then there is body filler for the rest.