Where do you live? A few of us have CNC machines on here, so engraving a TRC is no problem. Shipping would obviously be easier/cheaper if you're in the same country.
I have engraved truss rod covers both with CNC and laser. I'm just a hobbyist, though, but if you find someone near you who is like me, you might be able to get it done. Trophy shops might do it, too.