you need to be married to apply for a non imm 'O' visa, so enter on a visa exempt, obtain a 30 day extension, if required to get 400,000thbin bank account in Thailand in your name only, get married, then convert visa exempt to non imm 'O' visa 2,200thb, no need for a tourist visa, but will need a throwaway flight out to allow boarding of a one way ticket.