Dale recommends the installation of an ashdrop at the back of the oven. One way to gauge oven temperature is to sprinkle some flour onto the floor of the oven. Dampers are an important element for regulating oven temperatures. For sourdough, a starter can often be made from existing sourdough bread. Steam can be added by installing copper tubes to trickle water onto the oven floor.
Large ovens tend to have complex damper systems, and a personality.
Alan Scott consults on oven design and construction and also builds ovens. Click on images for enlarged view. View of side hearth and side walls before construction of vaulted ceiling. This is a small oven, with a 4 foot by 6 foot hearth. View of finished vaulted ceiling.