this is getting boring, my government pension is 13 times a year and is not enough, my private pension can be paid every 3, 6, and 12 months. So unless I take the lump sum and then send an additional monthly payment it won't work, not only that it will be more effort and cost and more explaining at the immigration office, not very appealing.
when I spoke to my immigration office, they said wanted to see documents demonstrating the origin of the funds, they well may accept income as you describe, they said there checking for money laundering, but bear in mind they have there own view on what they want.
I doubt that 800kthb is enough to trigger anti laundering checks, as long as its not a regular occurance, if possible get the payment sent for "living expenses". If still concerned you call the Bangkok bank helpline, they could probably give you the latest details.
The recently introduced 50kthb per bank transaction or 200kthb aday limit in a day only checks who you are by face recognition.