Wow, that third bunny looks just like Rucy! Anyway – the string one is out! I once had a rabbit that loved going out on a harness. The one I used was none of the ones you showed. It was a thick flat harness made for kittens. You are right though that a rabbit on a harness can freak out and cause injury by trying to escape while on a leash or harness. With my bunny, I followed the guidelines of getting a rabbit used to it and how to hold the leash in a way that lessens the chance of injury from rabbit agility and rabbit hopping competitions sites. Here’s an example – http://www.rabbitagility.com/?id=59
We also practiced with it and got used to it within the house first. We also walked with him in a place where there were no other animals or people who could startle him. It was in a tall fenced in area. I have found that two of my three rabbits now get stressed out with just the harness on, so it’s a no go.
Also, like others have mentioned, there are things that can be dangerous even if your bunny is fine on the leash. Example: Some Raccoons can carry a deadly disease that is passed on via their urine onto the grass. And of course fleas and parasites can really be bothersome in places. So you just have to weigh the risks.