Mix flour, yeast, and salt. Add warm water and 1 tablespoon oil; mix dough and knead 6 to 8 minutes until smooth. Cover; rise 60 minutes until roughly doubled, included in prep time.
Brown sausage in skillet over medium 6 to 8 minutes to 160°F. Plate; cook mushrooms in same skillet 6 to 8 minutes until liquid evaporates. Promptly refrigerate toppings until cold.
Heat oven to 450°F; lightly oil two metal sheets. Divide dough into 4 balls; stretch into 8-inch rounds.
Bake bare crusts 6 to 7 minutes until set but pale, rotating pans once. Cool completely on racks.
Spread each with 1/4 cup sauce; divide sausage, mushrooms, mozzarella, and oregano among them. Freeze uncovered on trays until firm.
Before final topped bake, tightly wrap firm pizzas, label, and freeze up to 2 months.
Bake frozen on preheated metal sheet at 425°F for 15 to 20 minutes until crust brown, cheese bubbling, and topping center 165°F. Rest 3 minutes; serve one per portion.
Reheat refrigerated cooked slices at 375°F for 8 to 12 minutes until toppings reach 165°F.