If you have time hire an agent who will coach your gf as to how to answer questions, including the purpose of her trip and temporarily adding the required funds needed in her bank account. The interview (in thai) itself is only 2 minutes. She can get up to a six month visa good for 10 years.
so did I. And my experience was that immigration was not interested proceeding that way. Weather language barriers or other reasons they saw 800k in the bank for the required time and did not want to bother verifying 65k a month.
My experience in Issan. No one is interested in verifying your deposits they simple want to see 800k in the bank for the amount of time before and after you apply or extend. Good luck