Pour oil to a depth of 2? in a 6-qt. Dutch oven and heat over medium-high heat until a deep-fry thermometer reads 350°. Whisk together salt, pepper, paprika, garlic and onion powders, thyme, rosemary, oregano, cayenne, and chile powder in a bowl; add oysters and toss to coat with seasoning. Add cornmeal and toss until oysters are evenly coated; dust off excess cornmeal. Working in batches, add oysters to oil; fry until golden brown, about 3 minutes. Transfer to paper towels to drain, and sprinkle with salt. Spread insides of rolls with mayonnaise, and divide oysters among rolls; top with lettuce, tomato, and pickles.