I would use a short chain, 8 inches if you are double staking. Coyotes are famous for jacking stakes out, but with double stakes they can't pull them. The more chain you have the harder it is to bed the trap and keep all the chain covered up. The only time you need a long chain is with single stakes and this helps to prevent the coyote from pulling up on the stake. Have you looked into using earth anchors as apposed to double staking? They are light to carry and coyotes can't pull them. I use the earth anchor with an 8 inch chain. They also make bedding the trap easy. If you look into them, save your money on the puller that they sell, you can't pull them unless you have very soft soil.