I'm not sure I'm understanding.
Your options are, as I see them:
1: get female KCs, have fertile KC eggs, probably get in trouble with neighbors
2: get female ducks of other species, have no fertile KC eggs, probably no trouble with neighbors
3: get male ducks, have no fertile KC eggs, no trouble
4: get no ducks, have no fertile KC eggs, no trouble, duck may be lonely and will cause trouble for chickens
Option 1 isn't viable here. Options 2, 3, and 4 all produce no KC eggs. Option 4 has the additional issues of potentially having a lonely duck and potentially injuring your chickens. With that in mind, why not pick 2 or 3? You don't have to incubate any mutt eggs you get out of the female ducks, if you get females.