Add the rice vinegar, sugar, and salt to a mixing bowl. Stir until the sugar and salt dissolve. Add the carrot and daikon, toss to coat, and let them pickle for at least 20 minutes.
Heat a large skillet over medium heat. Add the smoked meatloaf slices in a single layer and warm them for 2 to 3 minutes per side, until heated through.
Split the baguettes lengthwise, keeping one edge intact if you like. Toast them cut-side down in the skillet until lightly crisp.
Stir the mayonnaise and sriracha together in a small bowl. Spread the mixture over the cut sides of each baguette.
Fill each baguette with warm meatloaf, cucumber, drained pickled vegetables, jalapeño, and cilantro. Serve right away while the bread is crisp.