In this blogger's opinion the Part 15 Rules are sketchy.
They lay out a model scenario; a general situation; a typical setup.
But the Part 15 Rules do not attempt to anticipate the infinite possible situations that might arise, and therefore must be applied creatively.
Let's start with the known, and work our way outward from there.
At your house the Rules allow an AM transmitter with 3-meter antenna, 100mW to the input of the final RF stage. A well worn fact. Such a transmitter, if well installed, might reach 1,000-feet or better.