Yes, the F-35 is detectable, it just can't be targeted by any SAM known to exist today and no known BVR AA missile.
It's invisible to high frequency targeting radars.
It's enemies will know it's in the area and not be able to do anything about it.
“If we’re still planning for dog fights with the naked eye, everyone else in the whole world will eat our lunch. “
When have we ever allowed BVR air combat? Very exceedingly rarely. And in any case, the most expensive weapon in human history sold as a fighter bomber has less fighter capacity than an F-15 or 16.
Think Syria right now. There are Turk, Syrian, Russian, Jordanian, UAE, Iraqi, Israeli, French, and god knows who else flying there.
You are delusional if you think anyone will allow the USAF to torch off a missile beyond visual range at something where you don’t want it to be. They will have to identify first. The minute it is inside that box in daylight, it needs a fighter escort.
South China Sea? Ditto. Is it Filipino? Taiwanese? Vietnamese? Chinese?
Or maybe you mean the Baltic. Is it Russian, Ukrainian, Estonian? Pole? German? Swedish?
The bottom line, in anything except WWIII, there wont be any BVR except in very very rare cases.
OK. So the enemy fighters are in the above an airfield mix with our tankers, cargo planes and AEW in the air and trying to evade the attack - Shooting them with cannon, machine gun and short range AAM.
Enemy fighters and gun-armed attack planes are using civilian planes to get near our space and inside our flight paths.
How are you going to get in close to shoot in either case with killing our own planes or the nearby country’s civilain airliners?
Long range shoot-in-an-empty sky might happen. But hasn’t yet.