@Greg ****
It's across the river from Mukdahan. You can get there by bus, or you can fly into the airport there I believe (it's way expensive to fly in though).
It's one of the two thai consulates in the area that will issue a year-long, multi-entry Non-Immigrant Type O visa based on marriage to a thai without proof of finances.
The other one that issues that visa is the consulate in Ho Chi Minh City Vietnam