Spread cornbread level in a 10- by 15-inch baking pan. Bake in a 350° oven until dry and lightly toasted, about 20 minutes. Place in a large bowl. Add pumpkin seeds, cumin, paprika, salt, and pepper; mix.
Meanwhile, tear kale leaves away from tough center stems; discard stems. Cut or tear leaves into 2-inch pieces. In a 5- to 6-quart pan over high heat, bring 2 quarts water to a boil. Add kale and cook until tender to bite, 2 to 3 minutes; drain well. When cool enough to handle, squeeze water from leaves.
In a 10- to 12-inch frying pan over medium-high heat, cook bacon, turning often, until browned and crisp; transfer to paper towels to drain. Drain and discard all but 1 teaspoon fat in pan. When bacon is cool enough to handle, crumble and add to cornbread mixture in bowl.
Place trout, skin side up, in pan (in batches if necessary) and cook until browned on the bottom, 2 to 3 minutes. Turn with a wide spatula, reduce heat to medium, and cook until fish is barely opaque but still moist-looking in center of thickest part (cut to test), 2 to 4 minutes longer. Transfer trout to a plate and cover with foil to keep warm.
Add olive oil and onion to pan and stir often until onion is limp, about 5 minutes. Stir in kale, vinegar, and lemon juice. Add kale mixture to cornbread mixture and mix well.
Spoon cornbread salad equally onto four plates and top each serving with a trout fillet.