The setting is maneuverkillrange and I've always left it at 6000 ( max 30000 ). Not sure if that's feet or yards. I suspect feet.
I don't believe we should turn it off. If you get somebody on your six and 'force' them to stall and crash trying to blow your tail off, you should get credit for the kill.
We could adjust the range, I suppose. but I'm sure it'd still be possible to fly near a target base and wrack up prox kills when a flight of jabo P38s compress into Mother Terra.