Dear Lady Amherst,
In those conditions, here's how I'd rig up:
The fly of choice: Mikael Frodin's "Phatagorva" (3"-4" long) tied on a plastic tube with a tungsten conehead.
The line of choice: Loop Adapted Fast Sinking Shooting Head.
Rod of choice: Sage 9141-4.
Reel of choice: Bogdan #300.
I'm on my second dozen Templedog Stoneflies. See you June 5th: I'll be ready!