I am 5'5" and have a 17" Wintec A/P. With the hunters they require a snaffle of some sort, and they come in everything. I would start with a loose ring or a d ring.
The Wintec saddle is one of the most comfortable I have ridden in. I have used a friends Stubben for one show season whil I was showing her horse and I hated it. I have also shown in Collegiates and I still like the Wintec. The other good thing about the Wintec is they have the interchangeable gullet system. You can change the gullet when your horses back changes (my TB was growing so I went through 3 different gullets, and at $18 a piece it beat buying a new saddle when his back changed)
I would check out the KK Ulta Bits they are a little expensive but they work like a dream. They come in both the loose ring and the D ring.
Hope this helps!