My employer prefers to have the workers get a tourist visa, and then go to BKK with at least 21 days left on the tourist visa and convert it to a non-B. (I know, it would be easier just to get the non-B at a Thai embassy, but my employer is hopeless in that regard)

I heard from a BKK immigration official that you can get a 15-day visa exempt entry and, on the same day, go to BKK immigration and convert it to a non-B. Maybe it has to do with 15 + 7 day extension meets the 21 day requirement?

My workplace is near the Cambo border, so it would be a huge time saving for the workers to just make a border run, then travel up to BKK immigration the same day to convert to a non-B, as opposed to getting a tourist visa in Vientiane and then converting in BKK (a 4 day process with travel).

Any thoughts?

There are some recent reports that immigration will now accept 14 days left instead of 21 days.

Today I was able to get a 15 day visa exempt entry at the Cambo border, go to immigration in Bangkok, and convert to a 3-month non-B. We had a number of workers do this, with a discrepancy between immigration officials as to whether you needed 10 or 12 days remaining on the entry visa for them to change to a non-B.

Thanks for your report, confirms that they have now relaxed the rules regarding the number of days you need to have left to do the extension.

Seems even less than the previously reported 14 days.