What are the requirements for the non-O visa in Thailand, particularly regarding proof of income and experiences with Udon Thani immigration?

The poster is preparing for a non-O visa related to marriage but is unsure about the financial proof needed since they do not have the required 400,000 baht in savings. They meet the income requirement of 40,000 baht per month but need guidance on acceptable documentation for income verification due to changes at the embassy. Additionally, they are asking for others' experiences with the immigration process in Udon Thani.