I suspect that the H-6K's oft-quoted full combat radius is somewhat misleading, as there are no realistic prospect within the 5000km - 5500km radius of H-6K + KD-20 at the more extreme range envelop which would let an unescorted bomber of H-6K's capability venture that far. The oft-cited target of Guam, for example, would necessitate poor old Badger crossing a veritable gauntlet of USAF and USN assets before reaching notional firing stations, which drastically reduces its chance of success. One may cross reference how B-52s and Tu-95s are used to get some inkling of that.
That means realistically, any strike mission would have to be conducted under heavy fighter escort*, and that means the effective combat radius of the H-6K is perhaps much closer to 1,500 against near-peer opponents rather than 3,500.
Which isn't to say its range isn't useful, it allows for greater loiter time and basing far inside the well-protected Chinese interior within the best fortified bases, but under most realistic scenarios the 5500km radius reaching out to Guam and Northern Australia are theoretical exercise at best.
*There is one other way where relatively slow and lumbering bombers have a chance to penetrate, but that involves mass usage of nuclear missiles - that was the SAC's doctrine - but it obviously doesn't apply to China.
