I just got off the phone with a TurboTax agent who got me through to completion. The key is to not use the personal sales radio button (because there's no way to get to the finish line using that route) - instead mark self-employed. Continue through with that, and then I think we entered another self-employment form under wages and income, but now that I've actually completed everything, I can't go back to see what form I entered. But I do know that there's a form where it asks you for a business code and you use 999999. (six 9's).
I hope this helps anyone, because I definitely got to the finish line using this route. Maybe if someone finds this and successfully completes it as well, they can fill in the blanks I missed.
Good luck!
