"A quick Google search suggests that the combat radius for the F-35B on internal fuel is 505 nm. Not too shabby, "
Did you read the 2020 CSBA Study? Slide 4 entitled "Threat inside 1000nm may prevent CVW or air base operations"??? It shows at least 7 PLA missile types that can reach out over 550 nm.................................. and a couple of JH-7a Brigades can deliver circa 1200 tones of ordinance a day at 550 miles off the Chinese coast without refuelling.
They state that the Outer Air Battle uses distributed air defences with CAP's at 800 -1000 nm out ..............