@Andy ***********
Yes, but then your stay also is terminated.
There’s no official regulation regarding this and therefore between you and the IO and immigration you use.
The regulations gives three alternatives regarding financial requirements
(1) Income with affidavit letter.
(2) 800K baht
(3) A combination of (1) and (2) 800K in total for the extension.
Even the (3) is not accepted by all immigrations for extensions. So if they will accept this alternative without any regulations is between you and them without any regulations.