You are correct. Perhaps the moderators should filter some of comedians and editorials. The OP needs legitimate feedback. He is not a farang asking for ways to stay in Thailand without a visa or trying to screw the system.
If I had an immigration history like yours, and really only wanted to stay May-June, I would have a return air ticket (paid) for the US and present it to the officer. Getting another TR might be difficult if you are flagged in the system.
Try free standing bank branches. Mall branches are filled with normal banking customers and are really too busy to handle foreigners trying to open accounts. Also, their employees aren’t trained to do so. I believe that your visa should allow you to open an account.
Non-O from US for retirement requires insurance; so will subsequent extensions, as does O-A.
Perhaps start with tourist visa from US, then obtain 90 day non-O from Thailand immigration and then a one year extension of stay. This method will not require insurance.