Just thinking out loud here, and not really answering your query, but ...
I kind of like the form of the Hardrock 50+ amp. You spec'd no display, but would it hurt to have a little OLED display tell you radio health and status? I haven't looked for it but it seems a little display might be in the baseline already.
Of course, I'd have headphone / key / and mic inputs on the front, keep the antenna on the back. Maybe keep the sbitx power connector the same? Where do you want the ethernet connector and USB ports?
No volume / tuning control at all? I know headless is what you want, but it would be good to be able to make a CW contact without a computer attachment.
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Mike KB2ML