Well... (Could be a deep subject here.) You could do the alternative of a full multi-mode HF rig to do the job, with minimal modifications to audio and muffin fan finals cooling. For AM, Kenwoods, Icoms, even Alinco, can do the job with a 15W carrier, even though most will MAX to a 25W carrier, but it is recommended to stay 20W, or less. Stay away from Yaesu for AM TX'ing. They will be power hungry, drawing from 15A to over 20A of current at 13.8VDC. Plus, you could do USB option. Then, have the option of the other side, the RX portion of the rig to RX on site. On the TX side, look for TX audio FREQ response, the wider, the better. On older rigs, you might be able to widen the audio. Anyway, the option of using an HF rig for HF TX'ing, as an SW TX, has been done for +40 years now. Passing though.