Using a different bit for start of ride/ conditioning

Background:
My mare is fairly competitive, especially when she is great shape. I have the most issues slowing her down to a sane pace when we are on conditioning rides( about 1/2 the time with her pasture buddies, who do fast LDs. We do midpack 50s and multidays) when she will get very competitive. I currently use a 3 piece snaffle that she will listen to ( eventually), but I do not like to have to pull hard on her, which I do have to do when she really gets going. During an endurance ride, she is generally pretty calm and relaxed - 1st 5 miles occasionally have some idiot moments but they are decreasing. During the 2nd half of a 50 or on multidays, I often ride her with a rope halter if the trail is not overly technical. We do some low level dressage work and she is very well behaved solo or with a small group of non-competitive horses out on the trail. I can slow her down/ get her to focus with some low level dressage movement ( yielding, shoulder in, etc) on the trail, but I ride on alot of narrow trails where that would not be a great idea.

My question:
Would it make sense to try her in a sightly stronger bit - currently thinking a short shank snaffle ? I think that it could (hopefully) , get the message across to her without me having to yank on her mouth.

Any advice would be welcome

What about a pelham-type bit - either a “real” pelham or a western bit that also allows for double reins (like this- http://www.nrsworld.com/dutton-bits/dutton-short-shank-dogbone-bit-3391). Start with both reins or maybe just the curb rein, finish with the snaffle.

Gag fulmer snaffles used with two reins are useful in this situation.

http://www.bombers.co.za/endurance/bits/fulmer-gag.html

How about a Myler combination bit? I recently switched to one as I’m transitioning my dressage horse to trail riding. I found him to be much lighter in the bridle and he isn’t hanging on the bit anymore, plus it’s given me that extra control when he gets amped up.

I really, REALLY recommend using Myler bits if you are going to use a bit. They have such a wide variety of mouth pieces available which have much smaller and smoother joints that nearly any other brand. a fatter mouthpiece is not more comfortable to your horse, quite the opposite.

That said, I found that a Myler Kimberwick like this:
http://www.mylerbits.com/dyn_prod.php?p=89-25025&k=88067
works nicely for a lot of horses. It has the “Comfort Snaffle” mouthpiece which is very smooth and comfortable for most horses. You can hook your reins to the bottom ring and adjust the curb chain to suit your needs and you have a nice moderate leverage bit. You can move your reins to the center ring and you have a snaffle bit because the curb chain no longer will tighten with rein use.

I have found the Comfort Snaffle mouth piece works for most horses with smaller mouths and low palettes (many Arabians) but the occasional horse just cannot tolerate a bit sitting onto their tongue and will fuss with snaffle bits. For those horses this ported bit might be just the thing:
http://www.mylerbits.com/dyn_prod.php?p=89-25335&k=88067

It gets the bit off the tongue and the horse is more comfortable. I had a mare that just was bizarre with her tongue, putting it over the snaffle bit, hanging out the side, fuss, fuss, fuss. I tried this kimberwick with the port and she became a happy camper.

Bonnie