First off, thanks for sharing this, Bill!
I am trying to visualize this. So if you are holding your leader above the tag, and both scuds are dangling in front of you, is the fly attached to the tag lower than the fly attached to the main tippet? In other words, is the tag longer than the "main line"?
I always fish my second fly/nymph off a tag, but usually a 6" - 12" tag. and the tag is usually about 18" above the "main line" fly.