Preheat oven to 450.
Saute' potatoes in two tablespoons of the oil for 3 minutes, or until golden brown, drain well and set aside. Heat remaining oil and saute' zucchini, summer squash, mushrooms, and garlic for 3-4 minutes, or until vegetables are tender. Season to taste with salt and pepper, drain well. Spread marinara sauce over pizza crust. Spoon sauteed vegetables evenly over crust. Sprinkle on potatoes and roasted peppers. Top with shredded cheeses. Bake at 450 for 11-13 minutes or until cheese is melted and crust is deep golden brown.