...On trail rides I have to hold her back constantly or she will be miles ahead of the other horses, even at a walk. I love her energy but if I don't have the running martingale on her, her nose is always in the air. If I give her too much rein, off she goes...
Just a suggestion, based on working with a sample size of ONE horse (Mia):
I'd work on her stop, and then use stops instead of trying to constantly keep her back. Mia will also leave the other horses behind. Rather than fight to slow her down, I get a better attitude if we just get ahead some & then stop & wait. Or I'll turn her back and tell her we need to go get the slowpokes.
I've converted Mia over to a curb bit. Again - if she wants to accelerate, we'll stop. Stop, dammit, I said! OK, that was from a few days ago!
I used to try holding her in on a snaffle, but that just increased her tension. Now we're working on keeping slack in the reins and doing a full stop if needed, so she will learn to relax and carry her head in a relaxed position for her. Trying to reassure her thru the reins and keep her calm was just too darn much work for me! I'd get back exhausted.
I recently tried a bit with copper rollers. The jury is still out, but it did seem to reduce her fussing and yanking on the bit - something she is entirely capable of doing with a curb bit, although it is easier to deal with in a curb. And she can prance if she wants, but I'll decide the ultimate speed by either stopping her or turning her back and forth.
Since I'm searching for the right answer for Mia, I can't tell you one! All I can do is share what is going well or not going well, and sympathize. It is a challenge, but I honestly prefer all the work to a dead head horse strolling down the trail uninterested in anything going on.