I use both my Percheron mares as saddle horses and trail ride them. My only issue with teaching them to bow is them having to come back up with a riders weight now on them. A light rider I don't see an issue with but someone heavier I would, and before someone takes issue, I am not some skinny minnie. I can mount from the ground but since hurting my back, I use either a mounting block, truck tail gate or get my husband to give me a leg up.
They do make great trail horses, in fact, my mare Smoke and I were featured in the Trail Riders magazine last year I believe for just this topic.