I agree with most of the above - there's no need to get rid of the gait, the horse is perfectly capable of going at speed while maintaining its gaits.
Here's my beef:
OP has a horse she loves, and does not want to sell, and is trying to figure out new things to do with said horse. At what point did she say she's planning on trying to make it to an NBHA Mega Show? I didn't read that part, so I'm not sure where you all did. There is not one thing wrong with trying out new things with a horse you love and enjoy very much.
Add to that, read this here: Tennessee Walking Horse From Florida Wins Non-Pro Division at the Extreme Cowboy Race World Finals - Mounted Shooting Horse Network
You TWH people are going to have to decide what your line is: is your breed versatile or is it not? I'm not trying to pick a fight or start any huge arguments, but it's something for many of you to think about. Quite a few are jumping all over someone for daring to consider trying something new with her horse, while many others go on and on about how they love the breed for its versatility.
I just don't see what the problem is with the OP wanting to run her walker on barrels, for fun
. That is what's it's all about, right? Sure, if she wants to start doing bigger shows, then she should probably get a more suitable horse. But I'm not sure when riding the right breed became more important than enjoying the horse you already own.