If an FCC agent comes to inspect your install all that matters is how the FCC agent chooses to interpret 15.219.
You could call the office you fall under the jurisdiction of to see if they could tell you what they think about your proposed install, but I wouldn’t want to draw that kind of attention to myself. You could read all the AM NOUO’s you can find, and see if there is a pattern to them. That unfortunately will not tell you what does not get a NOUO, just what gets one.
I personally think, and this is just my opinion so if you act on it you are legally responsible for all consequences, you should get an AM transmitter that is certified and use it as the included instructions recommend, without modifications. Then if an inspector comes you can show how your install matches the recommended install and say you made a good faith effort to be completely compliant with 15.219 based on manufacturer’s instructions. I think the best transmitter for that would be one that has no steps where the user is messing with pots, tuners, knobs, slugs, or anything else where the user could set it wrong possibly resulting in an overly high power input into the final stage. So for example, put a talking house in a weatherproof enclosure, use the included wire antenna and the included power cord, connect your audio cable, and be done with it.
The devil’s in the details, and the tweaks to get the most range that can be had under 15.219 are where the grey area comes in that can cause a NOUO to be issued. People are free to push the rules all they want, but I am risk adverse enough not to.
Add a ground radial system an inch or two below the soil surface.
The OP's question has been answered and several interpretations of the rules offered.
Thread closed.
Jeff, if you have further questions/comments please start a new thread.
Neil