So where about are you suggesting settlement?
That's a tough question because, if the Chinese begin sailing to North America in the manner I'm suggesting, their first settlement is going to have more akin with Spanish Guam than Spanish Manila.
Somewhat like how the Europeans rounded Africa or crossed the Atlantic/Pacific in order to bypass the Middle East and "plug into" known trade routes at different points, the Chinese in my suggestion are going to be bypassing Manila and crossing the Pacific in order to plug into a known trade route at Acapulco.
When using the North Pacific gyre, the Spanish used Guam as a last refitting point before crossing the Pacific. Spain even settled Guam for that purpose alone. Spain also began scouting along the Baja and Alta Californian coasts for another refit point after the Manila Galleon route was established. China is going to want/need a refit point in North America for the same reasons.
A Chinese "Manila" galleon will leave Asia, cross the Pacific, refit at China's continental "Guam", sail south to trade at Acapulco, and then cross the Pacific again for home.
Because this refit point can be anywhere along the Californian coast, I'm tempted to place it in San Francisco Bay where the Chinese would be close to both the gold fields and the Central Valley. That's too far north, however. It also unnecessarily lengthens the journey exposing shipping to foul weather off the coast. For their refit point, the Spanish looked at locations in Baja for those very reasons.
San Diego would be my suggestion. You've got a protected anchorage thanks to Coronado Island, there's water available, and it's far enough away from the centers of Spanish activity in North America during the period. Of course a Chinese refit settlement in San Diego is going to need naval stores in the form of lumber, masts, and spars. Those materials are available further north up the coast and that will eventually bring the Chinese to the Bay.
As for Chinese profit it also depends on what kind of industries boom after settlement.
Agreed. The settlement will begin as a refit point and then grow into much more.
Settlements in California and mostly elsewhere in the New World started as branching off points to discover more gold and more often then not the colonists discovered other resources and made a much more profitable use of them such as Jamestown and Tobbacco.
Again, agreed. It's a matter of getting them ashore in the first place so they can look around.
Therefore settlements made in this area would be settled in mind of not just supplying the ships...
They'll begin that way because nothing is yet known of the other resources which may be available. They'll grow beyond that role quickly however. While China's ATL North American refit point would be initially settled to fill the same OTL role Guam filled for Spain, China's settlement will quickly become something more than that because there are innumerable more opportunities in North America than on Guam.
Of course, the biggest flaw in my gibberish is
why the Chinese would want to bypass Manila in the first place. Some other European power takes Luzon but, while this new power wants to trade, it doesn't have access to Potosi's silver like Spain? Or Luzon revolts against Spain making trade there too unsettled for China? Who knows what the details should be? All I do know is that China will have to covet New World silver enough to want trade with Spain to continue despite Manila being out of the loop.