... If my numbers are correct one can meet the 5 watt EIRP FCC limit using a modest vertical driven with less than the 500 watt FCC max RF power. ...
It seems likely that when evaluating the radiated fields of these antennas so as to meet an FCC EIRP limit using only a NEC far-field calculation that higher fields are being unreported, and may exceed the fields that would be generated by the FCC EIRP limit at distances fairly close to the radiator.
The FCC guidelines specify far fields are to be used: "...
However definition for the distance to the far field found in antenna textbooks is not the same as the far-field definition applied by MoM software such as NEC.
The NEC far-field is calculated for an ~infinite distance, over a flat ground plane if one is defined.
The textbook far field applies to all distances beyond 2L²/lambda, where L is the length or aperture of the radiator.
Which one is favored by the FCC?