From everything I could learn there are federal court rulings that cover it.

If stopped by police you are expected to give your name, address and date of birth. If you do not carry any form of ID they would enter what you gave them into the computer in their cars. If nothing on you comes back they wou8ld of course claim that the info you gave them is not correct. They could then hold you until they could verify your ID. Usually they would ask that a family member ID you are provide some form of identification.

You might also want to think about the consequences of riding without ID should you be involved in some sort of accident where you would be rendered unconscious and taken to a hospital. Questions on approval to render treatment might be a problem. Also any special medical needs they must watch out for.