Position a rack in the bottom third of the oven and preheat to 500 degrees . In a skillet, cook the bacon until nearly crisp, 8 to 10 minutes. Drain on paper towels. Reserve the bacon fat.
Grease a baking sheet with 1 tablespoon bacon fat, place the pizza dough on top and press and stretch the dough as close to the pan edges as possible. Sprinkle half of the cheese over the dough; bake for 5 minutes.
In a pot of boiling, salted water, cook the brussels sprouts and cauliflower for 1 minute. Drain in a colander and rinse with cold water until cool. Transfer to a large bowl and add the sun-dried tomatoes, garlic, olive oil, salt and plenty of pepper; toss well. Spoon the veggie mixture evenly over the dough, halve the bacon crosswise and scatter on top; sprinkle the pizza with the remaining cheese.
Bake the pizza until the crust is golden-brown and the cheese is bubbly, 10 to 12 minutes. Let cool slightly before serving.