Awesome! If you're concerned with the corner hammock not being stable enough, I would put it lower to one of the shelves (like 2-3 inches above the bottom or the side shelf) so in case it doesn't work, your new chinnie won't fall 7-8 inches and potentially injure themselves.
Most pet quality chins weigh about a pound (show can get up to 1.5 or more I think). Go in your kitchen and find a can of soup, jar of spaghetti sauce, etc. and put it in the hammock. You want to find something that weighs 500g, 16oz, or 1lb (if it's liquid, 1ml is close enough to 1g, so 500 mL).
Edit: Also, that willow ball you have, if you got it from a pet store, make sure there's not a peanut in it. I was going to buy one from PetSmart, but they all had peanuts in them and I wasn't sure I could get it out without destroying that ball.