Same mechanism for the DTV by the way. One final bounce + one last extension should let you squeeze our almost 6 years (like the 9 months for the METV).
You said you own a US registered company. Then you should have some official document proving that. That plus proof of at least 500k THB in saving should get you the DTV visa.
The average past salary should do, if you can reasonably proof it (I.e. by notarized tax returns or the like). Your current employer needs to be a public company listed on stock exchange or a private company that is operating for at least 3 years, with a minimum combined revenue of USD 150 million for the last 3 years. You need to be a direct employee - not a freelancer. The LTR website is quite detailed as to criteria and required documents:
Either Thai, English, or the official language of the country you are applying from should be accepted. Pretty sure I never had to translate a bank statement in German language when submitting to the Thai embassy in Germany. Unlike the LTR, the DTV is locally applied for. For the LTR however, which is centrally approved, all documents had to be Thai, English, or properly translated.