Here's the dealio: a shorter rail is, generally, more stable than a rail that is taller. I won't get into the logistics of it, but that's just the way it is. I usually just build my rails tall enough so that my tips and tails won't get too near the ground when I pretzel or whatever. With that in mind, I build my rails at a height of about a foot and a half. Maybe a tad shorter. Hope that helps, dawg