I think proof of residence is required only in consulates using the e-visa system. If you apply the traditional way (in almost all neighboring countries like Malaysia, Vietnam, Laos, Cambodia), this document is not required.
Personal income of at least USD 80,000/year at the time of application
In case of personal income below USD 80,000/year but no less than USD 40,000/year, applicants must invest at least USD 250,000 in Thai government bonds, foreign direct investment, or Thai property
Health insurance with at least USD 50,000 coverage or social security benefits insuring treatment in Thailand or at least USD 100,000 deposit