Greetings to a coho saltchuck brother! I was out throwing flies at Swiftsure, Sekiu and Neah Bay since the mid-80's back when people would look at you like you had three heads for flyfishing out there. Well, I guess they still do!
Just Topwater and a few guys like us throwing the fat lines, and having serious fun!
Here are (at the time of the writing) over 3,000
baitfish imitations right here on the Flyfishing Forum...
As a flyguy with almost 20 years of ocean coho flyfishing and 11 years of striped bass flyfishing, I can tell you that the only difference between the two fly patterns are the placement of the hook. Stripers will get hooked on a 12" fly with a 1" fly in the front. Coho need a hook that sits back a little for larger flies like herring patterns, etc.
TUBES are probably the best way to get the hook back in the length of the fly, I will post some old proven tube patterns I've put some huge hooknoses on the line with.
Another technique is to use a longer shank hook like a 911s TMC but you can't beat the holding ability of a short tube hook.
You should consider asking Nrthfk (sparky) to post his baitfish pattern with the inverted pearlescent flash - it was a killer at Sekiu two years ago.
Leland is at his annual Idaho fishing outing (I can smell the Cubanos and single malts from here) but when he returns I am curious to read his response on this topic.