How do I obtain a Non-O visa in Thailand if my tourist visa is expiring soon?

Jomtien requires the 800K baht for the initial 90 day Non-O visa to be in the bank for 2 months before you apply for it.

So

if you got the money transferred in Nov 27th the soonest you can apply for the 90 day Non-O visa would be Jan 27th.

𝗗𝗼 𝗜 𝘀𝘂𝗯𝗺𝗶𝘁 𝘁𝗵𝗲 𝗽𝗮𝗽𝗲𝗿𝘄𝗼𝗿𝗸 & 𝘀𝗵𝗼𝘄 𝗺𝗼𝗻𝗲𝘆 𝗼𝗿 𝘄𝗶𝗹𝗹 𝘁𝗵𝗲𝘆 𝗻𝗼𝘁 𝗮𝘀𝗸 𝘆𝗲𝘁?

They will ask for the bank letter, updated bank book the day you apply and proof the funds were in the account for 2 months before you apply

𝗗𝗼 𝗜 𝗷𝘂𝘀𝘁 𝗲𝘅𝘁𝗲𝗻𝗱 𝘁𝗼𝘂𝗿𝗶𝘀𝘁 𝘃𝗶𝘀𝗮 𝗯𝘆 𝟯𝟬 𝗱𝗮𝘆𝘀 𝘀𝗼 𝗺𝗼𝗻𝗲𝘆 𝘄𝗶𝘁𝗵 𝗯𝗲 𝘁𝗵𝗲𝗿𝗲 𝗶𝗻 𝗯𝗮𝗻𝗸 𝗳𝗼𝗿 𝟲𝟬 𝗱𝗮𝘆𝘀 𝗯𝘂𝘁 𝗜 𝘄𝗼𝗻’𝘁 𝗵𝗮𝘃𝗲 𝘁𝗵𝗲 𝟭𝟱 𝗱𝗮𝘆𝘀 𝗹𝗲𝗳𝘁 𝗼𝗻 𝘃𝗶𝘀𝗮 𝗯𝘆 𝘁𝗵𝗲𝗻?

you can get the 30 day extension on this 60 day entry stamp and then you're correct, you won't have the required 15 days needed to apply for the in country Non-O visa at that office

𝗪𝗶𝗹𝗹 𝗜 𝗵𝗮𝘃𝗲 𝘁𝗼 𝗹𝗲𝗮𝘃𝗲 𝘁𝗵𝗲 𝗰𝗼𝘂𝗻𝘁𝗿𝘆 𝗼𝘁𝗵𝗲𝗿𝘄𝗶𝘀𝗲 & 𝗿𝗲𝘁𝘂𝗿𝗻 𝘁𝗵𝗲𝗻 𝗮𝗽𝗽𝗹𝘆?

Yep, you don't have the time (even with a 30 day extension) so you will exit/re-enter the country to come in on a new free 30 day entry stamp, that gives you the time required THEN you apply for the 90 day Non-O visa