Sparkle Dun variations work really well here, strange thing is I have never come across anyone else using them. Good idea with the snow shoe, get every bit of help you can floating them. Some years ago there was an article in FF&FT about using a double wing on larger ones. That worked well as well, but, like the original, never took off over here. Mind you most people look at you aghast if you even suggest trimming a hackle!
Cheers,
A.