I've read Modern Dry Fly Code many times and have probably read all of Founding Flies three or four times.

Marinaro had to have tall, separate wings because of the criss cross hackling pattern of his thorax dun. Valla notes on a couple of pages (I think it might be in the Hewitt chapter) how Marinaro loved to fish wingless skaters for the Eastern Green Drake. I think this indicates the importance of a tall wing to Marinaro rather than a distinct separate wing..