20,000 watts is not a big deal. You want a strong Signal, all day between Chicago and New York? A power level with some design margin is what you need. Provid

20,000 watts is not a big deal. You want a strong Signal, all day between Chicago and New York? A power level with some design margin is what you need. Provided the transmitter is 'clean' and modulated such that the signal stays inside the allocated bandwidth, it will not impact other users. (except if you are < 1 Mile from the transmitter. the poor selectivity in your receiver may be overwhelmed by this power up close). The question is how much bandwith and what kind is the modulation? Narrow band modes consume less spectrum, and they also transfer less data. A 50-100 khz band could be carved out of HF and given to this services. 500khz would be way to much. And you cannot take it from the Ham bands. They were there first.