In a shallow glass dish combine the sugar, salt, pepper, bay leaves, and 1 cup of the wine. Stir to dissolve the sugar and salt. Place the salmon fillet in the solution and add enough water to just cover the fish. Cover and refrigerate at least 2 hours, preferably overnight.
Remove and blot the marinade from the salmon. Lay the fillet on the smoker rack, skin side down, and cover with several layers of the sliced sweet onions. Place the alder wood chips in the base of the smoker and position the drip pan and rack. Add the remaining 1/4 cup wine to the drip pan. Cover and smoke in the usual fashion for 15-18 minutes. Transfer the fish and sliced onions carefully with a spatula to a serving platter. Garnish with the parsley and lemon wedges.