UPDATE:
I received a very simple letter from the IRS yesterday saying that "Your 2018 Form 1040 inquiry is closed. Amount due: $0.00".
So apparently they accepted my explanation of reporting the 1099-INTs on Schedule C. I imagine I will end up getting notices every year and will have to send in the same explanation and documentation, unless the IRS makes some sort of note on my account (I doubt that).
Thanks to those that responded with helpful comments.
Kevin
