Hey! HostBuddy (your favorite co-host) here!
For St. Louis visit stlcitypermits.com and then select housing conservation and pay the $90. At the end of the application you'll get the opportunity to select a date/time along with your inspectors contact information.
If you need a local contact let me know! I have done a lot of these. For the county, let me know which locality and I can help out. I have the paperwork for each one in the metro! Happy to help
If you don't want to get it permitted, you'll be fined at some point. I have had long conversations with the building department. They can't get to all of them at one time, but they will get to ya.