Yeah, 10 kHz would be great, but you would need "tinker" with the DDS and transmitter to get a pass band that decent.
Then, at ten kHz, on shortwave is problematic since more channel noise can decrease your listeners pleasures.
If you go AM you need a whole lotta power to keep the s to noise acceptable. For a free radio station that could attract SHARKS, since any idiot can tune AM, but much better radios and SWL ops needed to tune SSB.
I recall about twenty or maybe more years ago, I heard a VOA transmission with carrier inserted. It carried two programs. One on USB and another on Lower.
BTW talk about sidebands, CHU time signal only transmits the USB and the carrier. Its cool to see it on the SDR. Case in point, the Toronto parallel station CFRX. Its said the transmitter is a Kw double side band, but when I listen except certain times of day.. selective fading, carrier dropping down below here good fidelity is heard and so on.
The big ones 1 million watt ERP stations even have fades. I can hear about anytime of year the 500kw, maybe 3 megawatt ERP
India Radio station on 7550. But its a non hi fi copy.