Given the requirement to detect collisions and a process to reissue an ID for various legal reasons, I don't see a problem. In fact, don't use too many digits.

Given the requirement to detect collisions and a process to reissue an ID for various legal reasons, I don't see a problem. In fact, don't use too many digits. If you use too many digits, collisions will be so rare that when they occur nobody will know how to handle them. Better to have a process that gets exercised a few times a year at minimum.