If you exist on real estate you're going to pay rent to someone. Even if you manage to find some parcel of public land to operate from you're still paying a lease/mortgage on your shipping container kitchen and all of its contents. You're going to have to pay insurance on the operation.

The best bet would be to pool resources to operate a single kitchen with multiple individual pizza companies as tenants. Each could run their own prep stations but use shared ovens. But you're back to rent dominating costs even if it's lower than having your own kitchen and oven(s).