Ducks do better at foraging (when there's anything to forage, which here, is maybe five months of the year...) otherwise I'm told they eat more than chickens. I have so many birds I have no idea who eats what. They do eat a lot, but you plan to (and you must) harvest most of the males. I understand three ducks to a drake is the usual ratio.
I have only two little Welshie drakes at present, though, and DH loves them so I guess they're staying. I have a quad of American Buff geese and oh what eggs! I am hoping for goslings but little papa hasn't yet figured out how to use his equipment.
I don't think you overdid it. But then then I did just order a dozen Ancona eggs and a dozen mixed ones. We'll see what hatches out. Shipped eggs can be iffy. My DH is probably gonna feel some kinship to yours, whatever happens. Like you, I will slaughter the extra boys and maybe sell diy duck kits to people newly thinking about food security. I hear baby fluffies are selling out in the feed stores in South Texas as soon as they hit the shelves. Maybe that portends a hot market for small-fry bird addicts like us, too.