Can I transfer money from my wife's Thai bank account to mine for a Non O visa application in Thailand?

that's it, exactly what we did recently. you then go to

the US consulate and write an affidavit, 50 bucks,

the get the affidavit and original marriage certificate translated to thai.

then of to the MFA office to get approval.

then off to your Amphur with 2 thai witneses to get your thai certificate, called Kor Ror 22

then follow the immigration requirements, photos, map bank letters etc

they give you 30 days under consideration period where immigration may visit you

then after the 30 days you go to receive your full one year visa on the date they give you.

OR you get the marriage to your thai wife recognized in thailand and you just put 400K baht in a thai bank account in your name only and apply for the Non-O visa based on marriage to a thai which does NOT have a proof of origin of the funds

It's down to the discretion of the immigration officer. I had no problem doing that. Get a bank statement showing the transfer from your account to your wifes 'If' they ask. I used World Remit and would of used that as proof if I was asked.

Alternative: Apply for the Non Immigrant O visa based on being over 50 years of age at a Thai Embassy or on line before you make your way into Thailand. Get 90 days of stay on entry and after 45 days you can apply for the 1 year Extension of Stay based on being over 50 years of age. For the Extension of Stay there is no proof needed that the money comes from abroad.

YEs, to apply inside Thailand at Immigration for a conversion of the visa exempt entry or tourist visa into a Non Immigrant O visa based on being over 50 years of age the money (800.000 Thb) needs to come from abroad as a foreign deposit into your own bank account, or double the amount if it is a joint account with the missus.