I wouldn't put a martingale or an elevator bit, because in my opinion, this hides the problem but don't fix it. As Alyssa and India said, the lunging or working in circles are more efficient solution. Even if it is a lesson camp pony, if you talk to the trainer or owner of the camp, maybe he will help you find the right trick to fix this.
Alyssa B, I can’t lunge her because she is a lesson camp pony, I would’ve but I can’t 🤷♀️
Try riding her in lots of circles and grid work to get her listening
have you tried lunging before getting to get her tired out so maybe she in not so fast
Running or standing Martangale. Or an elevator bit it works really well on my horses you can even but it on the snaffle hole