Is it possible to do a 1.5 hour visa run at Naha Airport (OKA)?

Aren’t you working online? Many people are in your same situation and have done the following (below). You can set up a Delaware LLC online (don’t need to be a resident) and structure the taxes to be pretty damn competitive (sadly foreigners can’t open a HK account any more).

There are soooooo many jobs in Taiwan aside from teaching English. This isn’t Korea. Lots of companies hire foreigners in product marketing roles for their exports.