Ours in the coop is 5-gallons with 4 horizontal nipples. It lasts about month for up to 20 silkies. We put 1/2 teaspoon of RV water freshener in it and that keeps it crystal clear. I know you'd love whatever you use as it means clean water without a mess!
This sounds like you really have things going well. I busted out laughing when I saw Nico. We have fields beside us and for some unknown reason, these two don't poop in our yard. That's a bonus to the farmers I guess lol.
If you could design a way to hang those feeders and waterers even an...