So it's basically sounding like chickens just aren't possible. Bummer.
They're possible, but you have to meet their needs.

If you're willing to tolerate occasional predator losses you can forgo some of the security measures.
If you put your tractor inside electric poultry netting with a solar charger you can avoid most losses to ground predators. There are a few things that a solar charger isn't strong enough to handle -- bear and hogs primarily -- but it will stop dogs, raccoons, coyotes, etc.