Grease an 8"-square baking dish, and line with parchment paper; set aside. Cover shrimp with 1⁄2 cup of hot water and soak until soft, 25 to 30 minutes; drain, finely chop, and set aside. Grate daikon on the small holes of a box grater. Transfer to a 4-qt. saucepan with 1⁄3 cup of water and bring to a simmer over medium-low heat; cook until water has evaporated, about 35 minutes, and set aside. Heat 1⁄2 tbsp. oil in 10" skillet over medium-high heat. Add sausage; cook, stirring occasionally, until browned, about 7 minutes. Add reserved shrimp, the shallots, and 1⁄2 cup green onions; cook until shallots and onions are soft, about 4 minutes. Stir in sugar and half the salt; set aside.
Bring 1 1⁄2 cups water to a boil in the bottom of a 12" skillet. Whisk remaining salt, the rice flour, and five-spice powder in a large bowl; stir in 1 cup plus 2 tbsp. water and reserved daikon until a thick, porridge-like batter forms. Stir in reserved sausage mixture to combine, and spread evenly in prepared pan. Place pan in a 12" bamboo steamer, and place steamer over skillet. Cover and steam, until set, about 40 minutes. Let cool 1 hour, invert pan onto a plate, peel away parchment and cover loosely with plastic wrap; freeze cake for 30 minutes, or refrigerate overnight.
Mix hoisin, garlic chili sauce, and remaining green onions in a small bowl. Slice cake into 8 rectangles. Heat remaining oil in a 12" nonstick skillet over medium-high heat. Working in 2 batches, cook, flipping once, until crisp and golden, 3 to 4 minutes, and transfer to a serving plate; serve with spicy hoisin sauce, and garnish with sliced chile.