Are you sure you want such a tall horse? in trail riding, a very tall like horse like that can be a pain in the derriere. Your head hits overhanging branches, your horse will be hard to ground mount, she may not fit well into trailers, etc.
I used to ride a 17.1 hh Irish Sport Horse. He was the best horse I ever rode . Very strong, sure footed, great personality, but, I could not fit him into average size trailers. And I needed Cadillac mounting blocks just to get on.