Unclenick, right you are about that ladder rear sight. But get one that's got a tiny, gentle curve in it 'cause horizontal spin drift, like vertical trajectory, ain't linear. Being "close enough" with a straight ladder one compared to "exact and perfect" with a curved ladder one may not be good enough.
One other thing about ladder rear sights most folks don't think about is, they're easily adjustable for exact elevation settings when the target is at an up or down angle to the shooter. As long as the ladder is in the true vertical plane, the line of sight can be at any up or down angle from zero to 90 degrees; the trigonometric corrections are automatically made. So, put an extension arm out to one side with a weight attached hanging down and that'll automatically keep the ladder rear sight in the vertical plane.