Rio, have you looked carefully at the picture you pointed to as being the right setup? Take a careful look. I wouldn't want a horse of mine looking like that.
I don't know the girl and only posted the picture showing a little girl, no real strength and a curb bit.
Please do not insult her or her setup.
Insult me if you want but not her.
I personally ride in a snaffle but I have the experience and the strength if needed.
You are going to argue the STRENGTH and most think it is not need, you will use ground work, finess but in the end strength plays a bigger part.
If the horse goes into a buck spree, if the horse rears, if the horse spins and runs, if the horse refuses to go forward. It all boils down to , Do you have a good enough seat to ride anything out, do you have the strength both experience and physical strength to make the horse behave.
I will fight if the horse so chooses, I will not reason.
This post is about what to do to stop the horse while galloping??
I suggest a curb bit with a curb chain.