Well I don't pull anything when fly fishing since I don't troll (at least on the water

). My experience in the Strait is from Port Angeles westthe and I have seen coho on the surface near kelp beds near Freshwater Bay but I have also fished rips off of the spit and found salmon by casting clousers. If you have aggressively feeding coho that are being caught the way the OP mentioned (twitching a hoochie) my experience is that casting a flashtail clouser will often out fish other fly patterns. It's good to have multiple patterns to try if one isn't working but often a fly that matches the profile but stands out a bit will kill.
It's also pretty easy to get down twenty to thirty feet with a sinking fly line. I rarely ever fish clousers on a floating line as the rod rigged with a floater always had a popper attached.