Yes, but only once or twice, as there are only a few trails I know are for sure safe for galloping (others are not maintained and you never know what kind of dip, ditch, rock, log, etc. you may encounter. And she is super fast outside of the arena! Basically she will run anywhere else except for in the arena. Whether the arena is dirt, sand, or grass it makes not difference. Anyways, at this point I'd rather just put out a video when I can because explaining isn't really getting me anywhere.
My way will work. It's not just a theory. It's not just something that worked on "my" horse.
It works on all horses because it's like a horse pinning it's ears, then biting to put something on the move. It asks, then tells them to go. It's as simple and easy to understand as it gets. But like I said, if you're not a good rider and might get thrown, don't do it.
If it works at a walk, do it at a trot. If it works at a trot, do it at a lope, then run.