@Benjamin **************
a DTV E–Visa Dependant Spouse application just needs a Copy of your County Marriage Certificate, and, if your County Marriage Certificate is not in English language or Thai language, then a translation of your Marriage Certificate is needed (of course, a County Marriage Certificate from USA is in English already)
Now, you could perhaps be confusing things with Registering a Foreign Marriage Certificate to a Thai Citizen Spouse (Thai Citizens Married Outside Thailand) at a Thai local District Office
Of course, you will need to scan your County Marriage Certificate as a PDF, but that's about as much as any Thai Embassy/Thai Consulate needs for a DTV E–Visa application for your wife's DTV E–Visa application as a Dependant of you holding the Main DTV E–Visa