Who says it has to be a bar boy at all? For example if I am staying in a hotel where some of the staff is proficient with English, or maybe a restaurant where the waiter is proficient, or anywhere I find someone proficient, I would have no problem explaining what I am trying to do and ask for help with the translations. Maybe offer some money as an incentive.
In other words, it shouldn't be all that difficult to find somebody who will give you the Thai words and phrases you want, especially if there is something in it for your "helper".