Reporting in from HCMC: I got an SETV yesterday. Easy process. No wait at the embassy. They only wanted proof of travel in and out of Thailand. No other proofs. They did seem to look through my passport, however, to see how many other visas I had.
TLDR : Answer Summary
A user reported a smooth experience obtaining a Single-Entry Tourist Visa (SETV) at the Thai consulate in Ho Chi Minh City (HCMC), with no wait time and minimal documentation required—only proof of travel dates in and out of Thailand. The comments from others suggested that accessing Thai visas from consulates in Vietnam is generally hassle-free and there were inquiries about the typical processing timeline, questioning whether it can be done on the same day.