I am told that anywhere upriver of about Kalama or maybe even Longview, there will be no actual reversal of flow at the height of the flood tide. The current may dwindle to 1/2 kt, but it won't reverse.

The guidance I have seen WRT when to troll is when you get the sense that your lure isn't doing its "dance" due to current alone (based on the pulsing of the rod tip), it is time to get off the hook and troll for a couple hours.

In some parts of the river, and according to some schools of thought, it is trolling all the time (downriver) regardless of tide. That makes some sense, because the fish are headed upriver against the tide, and by trolling downriver, you are running your lure/bait right into their faces.

My plan when I go down is to watch what boats around me are doing, because collectively they probably know more than I do. There must be a few locals sprinkled amongst the out-of-towners.