Simpler to just stay on the OA extensions. Assuming she has 800,000 baht in an interest-bearing account, it would suddenly become non-interest (or very little) bearing, parking it in a Thai account to get a visa. The interest income alone might be enough to pay for the health insurance required by the OA extension....and then she has health insurance, which a lot of people think is important to have anyway.
Immigration is being deranged lately so who knows how they will react. I got a DTV just so they will stop bothering me, but I was in Thailand for only about 3 months last year.