Easy. You need a drake only pen. Only drakes allowed in there. Your female duck is going to be lonely by herself, but that # of drakes basically guarantees that she will be injured or killed. You could also always pick and keep your fave drake + the girl, send the rest. ...or you can let duck math take over, adopt about 15 more females, and have a giant happy flock! But keep that duck safe, keep her separate from the drakes.
Edited to add: From what I've read, your potential drake-only flock needs to be out of sight of the female duck. If they so much as see her, they will be aggressive. It's also much easier to rehome a female than a male.