You are more or less on the rigth track here so far as how l would set up.
Let me ask you this question. Are the fish taking the naturals off the surface or not ? or are they visible taking the pupa, emergence stage.
The flies l would choose to use are these.
Black and peacock spider.
This is a peacock herl body and a black hen hackle.
Black and silver spider.
Body is first half silver flat second half black thread or turkey herl , hackle black hen.
Also called a hen blackie with a gray mallard wing. which is also a great fly.
Try these guys
Davy