Too many holes in this horses training to be riding him out on trails to me. Use of any martingale for head tossing is wrong to begin with.
Either something is wrong with your mechanics, or former owner's or there are physical issues with horse.
But fix them, and not by using something to hide it.
Dental, saddle fit, chiro needed, horse not trained, or you are heavy handed, or jiggling reins or FO did, but whatever? Needs to be worked through, not forced into submission.
Horses make me a better person.