Yes, I believe the US Embassy in Thailand is no longer offering that service. So it means a trip to the US. However, you could try: 1 giving someone in the US power of attorney (and your original marriage certificate) to see if they could do it, or 2 contact a US Embassy in a country close to Thailand to see if it could be done there. You would still need to have the document legalized by MFA in Thailand, and then go to a marriage office or local amphur with all documents, and witnesses, to get your Kor Ror 22. Hope this helps.
A point to bear in mind: When your husband's name is translated into Thai it most likely can be spelled in different ways (I'm sure you know this). Make sure it sounds right. It is important to remember how it is spelled, and for obvious reasons, should be spelled in exactly the same way on any document(s) that requires it.