Cowlitzfisherman, I didn't misunderstand, I meant that you worked in conjunction with rules and such. I misworded it.
I also have fished the majority of the river. I meant the "snaggers" fish the upper end. I know the river from headwaters to mouth. I used to fish the mouth alot, you had a good channel for incoming fish, and also the channel narrows out for fish running upper chehalis river. And, all the years we fished or ran our sled near mouth of Sop, never saw the long leaders you're talking about either. Most were smaller leaders, most guys were using bait or tossing plugs. Never once saw the flossing you're speaking of. I was down visiting my Dad yesterday, so asked him about this, just to make sure I hadn't missed anything since he's fished the rivers there alot longer then I have. He's never heard of the fishing you've described either. Most of the guys he knows either used floats in that deep hole in mouth of Sop, or used the standard leaders and swept through. Never seen a leader of 10' feet.
Yes, parts of the Sop are that way, but usually only like 2 holes on the upper end. Most you could easily fish a 10' leader. Plus, if they were doing a proper upriver and drift through, wouldn't take much of a river to get a proper drift in, even smaler then the leader length. I was using the upper river because it's where you'll see the majority of the snaggers. You see them throughout the river of course, but biggest horde is the way upper river near Schaefer Park. I'm sure there are guys who use these leaders, but not near as prevelant as at BC. Like I said, I've only fished BC a few times, and every time I've fished it I've seen majority of guys use this method. We opted from then to use sled and fish below that area. Why deal with that mess? So, hope that clears things up for you. We sled the chehalis mostly, and depends on time of year and what we plan to target, depends where we launch and were we fish. Have ran sled up near that hole many a times. Lots of fish travel up that way to enter Sop. So have seen those guys fishing quite a bit when we weren't trolling lower river. Never seen long leaders. Maybe 4-5' max, and that's only a few doing that.