Definitely teach her to neck rein. Its very important.
Does she respond to leg pressure? If not, get her working with that too. Leg pressure and neck reining will work hand-in-hand believe it or not.
Work on transitions so that when your asked to lope/trot/walk you can just gently squeeze with your legs and she responds.
Having her listen to your seat is also very important.
Loose reins are also very nice. Since your horse's head carriage is naturally higher than most stock horses, I suggest getting Romel Reins-
Notice how the reins look, and how the person holds them. Also notice the horse's head set.
Of course, you can show in your regular split reins if you more comfortable in those. Personally, if I ride horses with high head carriage, I ride in romels.
Then of course, your horse has to know how to neck rein.
My horse learned to neck rein in a couple of weeks and shes still not sure.
When your in the pleasure class and they ask you to rotate and the judge or the judge's assistant ISN'T LOOKING you can quickly use two hands and rotate the horse. As long as the judge didn't see it, it doesn't count.
I don't encourage this, but thats just if the show is in the matter of days.
Oh and by the way, we do actually see a lot of Clydesdales and Drafts at our local 4-h shows and open shows. (: