I don't think that I will have a problem with them ruining the vegetation as I have 320 acres (most of that pasture) to use, as long as I move them often enough. How often do you think they would need to be moved if they were in a 160' square electric netting paddock? Another possibility is that I can let them out around 10 (I believe that they are pretty much done laying by 9) to free range and then round them back up at night. This would definitely cut down on feed costs and allow me to not have to move the paddock as often.
Is there any type of trailer structure that can have just nest boxes or something for them to lay in? Could they be trained to lay in some type of mobile nest box that I could just move when I move the paddock? Will they come there to lay eggs but not hang out and get it too messy?
As far as predators, we have owls that like to get the chickens at night if we don't lock them up. I was thinking that they would go after the ducks if I don't lock them up. Any ideas on how to protect them from owls? maybe a LGD?