Have fun!
I've never hatched silkie ducks, so I don't know if they're different from Indian Runner ducks or not. But I have great luck running the incubator with very low humidity, using a standard auto-turner, then locking them down in egg cartons when I notice the first duck has pipped internally (I start candling around Day 23 to check for this). I lockdown with as high humidity as I can manage.
My latest hatch rate (this past weekend) was 85%. My hatch rates range from 75-95% with most of them in the 85-90% range.
You're here in NC, but I don't know if your humidity is similar to mine--where the heck is Rougemont? lol Whether your AC is running or not will impact your ambient humidity too, but really, I just don't ever go wrong using a very low humidity.
I'm going to start spritzing my eggs with water every day, to see if it helps soften the shell and raise my rates even higher. But I'm pretty happy at 85-90%.
Good luck and have fun!