Is 30 days enough to apply for a Non-O visa in Thailand, and what are the requirements?

Non O has no health insurance requirement.

𝗜 𝗼𝗻𝗹𝘆 𝗵𝗮𝘃𝗲 𝟯𝟬 𝗱𝗮𝘆𝘀 𝗼𝗻𝗰𝗲 𝗜 𝗮𝗿𝗿𝗶𝘃𝗲, 𝗶𝘀 𝘁𝗵𝗮𝘁 𝗲𝗻𝗼𝘂𝗴𝗵 𝘁𝗶𝗺𝗲 𝘁𝗼 𝗮𝗽𝗽𝗹𝘆 ? <- That's totally dependent on whether you can get your act together, get the 800K baht in a thai bank account in your name only and still have enough days left on your stamp to apply. If you need more time you can apply for a 30 day extension though so in 60 days you should be able to do it

𝗔𝗻𝘆 𝗮𝗱𝘃𝗮𝗻𝘁𝗮𝗴𝗲/𝗱𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝗰𝗲 𝗶𝗳 𝗜 𝗮𝗽𝗽𝗹𝘆 𝗳𝗿𝗼𝗺 𝘁𝗵𝗲 𝗡𝗼𝗻 𝗢 𝗵𝗲𝗿𝗲 𝗶𝗻 𝘁𝗵𝗲 𝗨𝗦 𝗮𝗻𝗱 𝗮𝗿𝗿𝗶𝘃𝗲 𝘄𝗶𝘁𝗵 𝘁𝗵𝗮𝘁 𝘃𝗶𝘀𝗮 𝗮𝗹𝗿𝗲𝗮𝗱𝘆? <- that is a decision YOU have to make. Either get it in your country before you come here (which might require you carry insurance, READ the requirements at the consulate you'd be using)

𝗙𝗼𝗿 𝘁𝗵𝗲 𝗳𝗶𝗿𝘀𝘁 𝟵𝟬 𝗱𝗮𝘆𝘀 𝗜 𝗱𝗼𝗻'𝘁 𝗻𝗲𝗲𝗱 𝗵𝗲𝗮𝗹𝘁𝗵 𝗶𝗻𝘀𝘂𝗿𝗮𝗻𝗰𝗲 𝗼𝗿 𝟴𝟬𝟬 𝗸 𝗯𝗮𝗵𝘁 𝗶𝗻 𝗮 𝗧𝗵𝗮𝗶 𝗯𝗮𝗻𝗸, <- Getting the 90 day Non-O visa inside the country (or the year extension after that doesn't require any insurance.

BUT

You DO need to have the 800K baht in a thai bank account in your name only to apply for the initial 90 day Non-O visa. Some offices require you prove it was transferred in from abroad AND at least one office Jomtien requires it is in your account for 2 months before you apply for the 90 day Non-O as well.

On what basis are you applying for a Non-O ?