As a horse owner, I'm impressed with your scale. As a perpetual kid, the rocking horse is a dream project---just what would appeal to anyone's idea of a great toy.
You'll figure out the bridle and saddle and I'm sure your fine eye will find a solution to the materials. By all means, when you master the mold issues, do make multiples, and consider marketing them to the horse people, too. We see a lot of really nice collectibles at the bigger shows which make nice geegaws for display at home and in the tack rooms/barns.