Troll faster, over 2mph now. Those speeds you were doing in June is what I run in April/May on Champlain. Mix it up for salmon, try one speed, then speed up, go with the wind and against it. S turns are good, gets the lure to drop and then speed up.
I prefer to run streamers myself, but do run spoons which catch more fish for me. Salmon can be picky depenging on the lake as well. I can dial in certain colors/techniques on Champlain for salmon that won't work as well on other lakes.
Sometimes I can catch salmon 5 feet down and 5 feet back on downriggers, other times they want it 100 feet back. Moderate wave chop on the water is usually good for salmon when they are shallow. This time of year fish are deep, like 30 to 50 feet down.