That sounds like you have built duck-heaven! I don't think i can help you out with my flock, i have the same drake problem here and i do not have a way to separate at least some of the drakes from my flock. The Pekin drake is a real problem, because he is a big and heavy guy that can injure lighter ducks. Are you able to divide your fenced-in area with just a 1' temporary fence? - The Khaki will be able to hop over that fence, the Pekin won't.
You need at least six ducks for these two boyz, maybe
@WVduckchick knows somebody who would like to rehome some duckies.
Should you decide to get some mail-order ducklings i recommend two Runner Ducks and two White Layers. The Runners will be able to run away from the Pekin Drake (keeping him from turning into a fat blob) and the White Layers are heavy enough to keep up with a Pekin Drake. From duckling to duck it is just a little over two months (13-15 weeks), but your drakes may calm down somewhat when they are able to see the little ones.