Coat with liquid smoke and Worcestershire sauces, then coat with the rest of the spices. Mix the 2 salts together and coat evenly, then coat with Demerara and then golden brown sugars. Dice up onion and sprinkle on top.
Let sit for 24 hours in fridge, then turn over so the skin side is up and the meat side is in the liquid mixture. Let it sit for another 24 hours. Rinse off the salmon and tack up for 1 1/2 hrs, and it will be ready to put in the smoker.
I use a Bradley smoker and set the temp at 170° (pre-heat before putting salmon in) and use hickory pucks (get the smoke going before putting salmon in) for 5 hours. At the 4-hour mark, baste with a mixture of 3 parts maple syrup to 1 part golden brown sugar, and then put back in the smoker. Glaze again at the 4.5-hour mark and remove from the smoker after another half-hour.