I have used a dry brine but have gone back to a simple wet brine
1 gal HOT water
1 1/2 cups kosher canning salt
1 cup brown sugar
juice of one lemon (you can use the bottled stuff)
1 large onion, chopped fine
4 large tblsp of minced garlic
mix well
Put the fish skin up in the brine and into the fridge from 4-6 hrs
remove and pat dry
air dry for 3-6 hrs depending on air temp.
optional; marinate in soy sauce for 1/2 hr,pat dry
optional; lightly coat with brown sugar or rub of your choice
always smoke with Alder to the way you like it.
Also, i have always had better luck with the bellies and thinner filets
really thick slabs don't ever seem to come out the way I like