What can I say... I am drooling over the "waking pool" and the fish you rose this season. I'm trying hard to finalize my schedule, just found out I will be in Cal third week in Oct.
I'll know soon what my schedule will be.
Anyway - my theory on surface flies.
My experience has been that summer fish are most prone to torpedo a surface fly at first light or last light once the caddis pupae line the shoreline stones. This is why each fall I shiver at the thought of skating my caddis patterns through the heads of holding pools, where the most aggresive fish are at first light, and where the antsy ones push to at dusk. Steelhead distinctly move to the shoreline for the night. I have flashlighted steelhead so close to the shore while walking at night that it was astounding and they did not always scream for deep water (depending on how calmly you lit the water). In the morning, when I jump on overhanging rocks to reach the middle of the river steelhead scurry out from under the rocks where I am sure they spent the night.
The first summer I moved out to PNW I drove to the Washougal. It was early summer and the springers were in. Talk about getting a newbie in heat! Also learned they are nearly impossible on a fly, but went upriver and crashed in the car. Woke up at first light near the bridge pool with the one car slot. The entire pool lit up like a springer pool down river but they were all bright steelhead! I will never forget that morning.
It took me a while to get the confidence to fish surface flies but it soon became apparent that (a) these fish are fully aware of what's overhead at all times (b) there is something to the surface fly that reaches down into the fish' psyche and triggers a lunge (c) fall caddis make them drop their guard (d) nothing stains the shorts like a placid steelhead pool when a big steelhead charges your surface fly.
All that being said I once rose a big steelhead from over 6 feet of water at 2 pm on a sunny day, go figure. I also read of guys raising BC steelhead in near freezing temps too. The time of year I do well on top is fall when the caddis are active.