Tony Torrence's Blue Boy sea-run cutthroat fly. Use the fly on a clear sinking line or Poly Leader swung and stripped in early morning hours. It’s a perfect time to fish Sea Runs in the Pacific Northwest!
These guys did it by modifying a guide gear tent, though you can now get the actuall pas through in silicone. Still not sure you should do this in a non fire treated tent, even with a curtain and floor of fire cloth.