Thanks for the info. I have a Thai bank account but haven't put the 800k baht in yet (waiting for the USD/THB exchange rate to improve). It seems that I have 2 options then:
1. Go to Cambodia or Vietnam, and get another 90 day non-o retirement e-visa before returning to Thailand.
2. Do a border run to Laos, come back in with a visa-exempt stamp, then convert to a non-o 90 day visa (tm.86).