I've been living in the country and learning speaking Thai for ten years. Before that I did the same in Indonesia. You're dealing with the wrong people mate. My local merchants are more on the ball than I think you or your bar girl are.
Easier than Thai. At least it is in Roman script and rones are clearly indicated. I would have thought 4 years along enough to get by. I found the Vietnamese quite mercenary in the tourist areas. But that happens everywhere.