She may be able to ride ( stay on) but it sounds like she lacks the softness and feel you need to really train a horse right.
You don’t need spurs, harsh bits and gadgets to restart your mare and it sure won’t make her more confident or help her spooking to use harsh methods to push her through training issues before she is mentally ready.
There is nothing wrong with using a snaffle and running martingale when riding this mare if she needs mild contact for security. As time goes on and she starts gaining confidence, you should be able to ride without it.
The word Snaffle refers to the cheek of the bit, not the mouthpiece. There is no such thing as a Snaffle elevator or gag. You can have a single joint elevator or gag but it’s not a Snaffle. Adding a curb strap simply prevents over rotation of said bit, it doesn’t make a bit a “curb bit.”
Sometimes, gaited horses have been trained w so much leverage to get their heads up and back, they pin their chin to their chest which makes them unridable. The gaited people use running martingales a lot. We’ve had very good luck restarting those horses on the ground on a lunge line and a chambon. It’s a very, very slow process. There is little to no backward pressure. When the horse raises his head, the chambon applies poll pressure much like TTouch. I know you are committed to this horse, so this might be an option. Try to analyze how she’s been trained and figure out how to undo it. Good luck.
