I'm looking to buy a horse, mostly for trail riding, hoping eventually to get into longer-distance rides and competitions, like 20-30 miles, maybe even 50 milers if horse and I get into good enough shape. I'm a tall gal, and big besides, so I LOVE riding drafts. I'm pretty sure a draft isn't suited to lots of riding, stamina-wise. Am I correct in that assumption? Would a half draft be suited, or should I look for a non-draft horse that fits me? If a half-draft MIGHT work, what sort of things should I look for, or should the vet look for at the pre-purchase exam?