In my opinion, the best launch facility near Union is at Twanoh State Park. It's a two lane ramp with dock space and plenty of parking.
Mid-September you should be able to find some silvers. It's usually a tough bite though. Those Hood Canal fish have the case of lock-jaw. I can't say that I've been successful there. Check out the usual haunts such as the shoreline north of Hoodsport hatchery and across the canal to Dewatto bay.
You can usually see the silvers cruising along the shoreline of the many bays that dot the canal. If you can get close and be stealthy, try casting small spinners at them. Otherwise, you can troll gear like everyone else. The usual gear should work.
Good Luck!