What's a reasonable hanging feeder capacity for 10 hens? I don't want food sitting and getting stale but I also don't want them running out too often. I saw an 11-pound unit at the feed store that looked like it would fit nicely under the nextboxes (so they couldn't perch on it!) but I wondered if that's big enough or if I'd need two that size to be able to go away for the weekend without them running out?