We fished for Salmon in BC waters for many years, mostly north of Campbell River. There are many rig set ups, with or without flashers. Cut plug herring are used by many fishermen:
Some use lures, spoons, plugs, or hootchies behind a flasher. Almost as many combinations as you can imagine. We used a 6 oz "banana" trolling sinker and about a 6" to 8" leader with a double hook rig baited with a cut plug herring almost all the time. Many of our fish were hooked after kicking the motor out of gear and letting the boat come to a stop. You can fish pretty deep using this method, sometimes called "motor mooching". Suggest you don't do this if using downriggers, which I hate to use, you will get massive tangles.
If you can find a guide or charter fishing the areas you want to fish, I think it is well worth the money. You can learn a whole lot in a short period of time instead of hit & miss on your own.
For bottom fishing, plastic jigs tipped with bait have worked for us. Again, lots of possibilities.