I remember following a thread by
@K0k0shka where she had a smart-ass cockerel who kept billing out extravagant amounts of feed, and her search for a truly waste-free bucket feeder to foil his billing habit. Took me a while to find it.
https://www.backyardchickens.com/th...s-and-questions.1356048/page-66#post-23067900
If you read the posts before the above one, she tried a couple other popular PVC elbow feeders that were useless before finding
@aart's article with the feeder that worked.
https://www.backyardchickens.com/articles/aarts-waste-free-funnel-bucket-feeder.67218/
I used the principles of aart's design and modified them to make a hopper style feeder to save space in my little beach-city coop. I know you have a hella lot of birds, but you could probably modify it the other way and use a plastic trash can instead of a bucket to feed your horde.