During the summer there would zero bass below the thermocline in this part of the province. The temperatures would be well below their preferred range. That doesn't mean smallmouth aren't deep, or won't go deep, but not below an established thermocline.
There are numerous factors at play for what is stocked and where (some of which is political). Brook trout are harder, more expensive and are the most sensitive to environmental factors. Rainbows (of the "trouts") are the easiest/cheapest. Rainbows and smallmouth bass also are closer when is comes to their preferred water temps and both don't "need" quite the same water quality as brookies.
And if we're talking about spawning (not a factor for some stocked fish) brookies, which are a char not a trout, spawn in the fall same as the lake trout char. So while they might use similar areas for spawning they do happen at different times of the year. Rainbows are a salmon and spawn in the spring in most cases