I was thinking about how this could be done and make the health department happy and prevent the normal reaction, i.e. the customer would simply pile on masses of ingredients, making for a horrible pizza and and excessive food costs. The answer is really simple: Make it cafeteria style, i.e. portions in pre-measured small containers. You go through the line, get your dough, your sauce and whatever ingredients you want, then proceed to the make-tables. I would also suggest posters explaining how and also instructions on the menus.
After it is made, it goes to the kitchen, it is tightened up a bit and cooked.