For obvious reasons our dogs were kept on stakeout chains or confined in exercise pens at field events. We made the stakes ourselves out of rebar and always used safety swivels. The dogs preferred the stake out chains as they provided increased mobility.

The chains were only 4 feet long for safety reasons. If the chain is too long a dog can quickly become entangled, panic and harm themselves. Six feet probably wouldn't be too long for a dog the size of Bear as long as you were with her. I wouldn't recommend 12 feet because of the dangers of entanglement.