Combine water, 1 tablespoon oil, 1 teaspoon sugar, and yeast in a large bowl; let stand 5 minutes or until foamy. Lightly spoon flour into dry measuring cups; level with a knife. Combine 2 cups flour and 1 teaspoon salt, stirring with a whisk. Add to yeast mixture; stir until a rough dough forms. Turn dough out onto a lightly floured surface. Knead until smooth and elastic (about 10 minutes); add enough of remaining flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will feel tacky). Place the dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85°), free from drafts, 45 minutes or until doubled in size. (Press two fingers into dough. If indentation remains, dough has risen enough.)
Preheat oven to 450°.
Heat 2 1/2 teaspoons oil in a large nonstick skillet over medium-high heat. Add sliced onion, remaining 1 tablespoon sugar, and remaining 1/2 teaspoon salt; cover and cook 15 minutes or until golden brown, stirring frequently. Spoon into a medium bowl. Add remaining 2 teaspoons oil and mushrooms to pan; sauté 5 minutes. Add Madeira; cook 30 seconds or until liquid evaporates. Add mushroom mixture and bell peppers to onion mixture; stir well.
Combine cheeses in a small bowl, and set aside.
Punch dough down; cover and let rest 5 minutes. Divide into 12 equal portions; roll each dough portion into a 5-inch circle on a floured surface. Coat 2 baking sheets with cooking spray; sprinkle each with 1 tablespoon cornmeal. Place 6 dough circles on each baking sheet. Top each dough circle with about 1/4 cup onion mixture and 1 tablespoon cheese mixture, leaving a 1/4-inch border. Bake at 450° for 12 minutes.