A Koxinga analogue would help a lot. He himself died a century+ ago.
Anyway, Qing isolationism and arrogance are overstated, IMO. What did Britain have to offer in 1790 that was immeasurably superior?
militarily, man for man, they were significantly superior already. Navally, incomparably superior. Culturally? Well... not so much
The point is that Britain wanted to be recognized as 'equal', not 'superior'.
Similarly, what is often forgotten is that China did sign a treaty in the 18th century recognizing a European state as its equal. We don't discuss it ecause that nation was Russia.
(I am sure IBC is making a "Haha" right about now).
Why Russia? The Qing were terrified of a threat from the steppes and Central Asia.
True. But most Chinese states were oriented to the threat from the steppes, because that's where all the serious threats came from. Anybody coming from the sea was a pirate or a tributary state.
Hmmm... Maybe if Koxinga HAD been a real threat, they might have changed their minds?
Seriously, though. The Qing emperors absolutely insisted on treating Britain (diplomatically) like, say, Vietnam, whom they could treat as a vassal. The first time that they were even prepared to consider the possibility of a British ambassador was when the British besieged Nanjing and blocked the Grand Canal in the First Opium War.