She is a beautiful dog. That's what "I" would do, start saving up and collecting materials for a fence. It will make everyone happier, Koda won't have to be on a chain, the chickens can be protected, Koda won't get hit by a car, and you'll have much less stress and worry about the liability of having a large breed dog roaming loose.
As for fencing suggestions: I suggest a physical fence. Keep my dogs and animals in, keeps others out. Keeps "people" out, I'd be more worried about human tresspassers than animal. If you cannot afford a more solid fence, like chainlink, cattle/field/dog wire fencing, may want to look into a physical electric fence. The one where you put up several strands of wire above ground and connect them to a fence charger. Anytime an animal tries to go over or through they get shocked. We use this with our horses, because it is easy to install, replace, and most importantly afford.
If you did not want a physical fence, I would take BeeKissed's advice and use the wireless radio fence. The one that permits the animals to come back in without shocking them. Also, another negative side to a wired radio fence is you have to remember exactly where the wire is buried. We "cut" ours by accident, growing up, several times by digging and that calls for finding where you cut it and repairing it. If you go with a radio fence of any kind, check the collars and test the fence regularly. Sometimes batteries run dead or the charger malfunctions.