There are a couple of elevation adjustable rear sights out there - Knights makes one and there is another company that makes one issued by the military (looks similar to the Mangonel sight; but I forgot the name).
However, I don't find the elevation adjustable sights to be that useful from a practical-use standpoint. A same-plane aperture no elevation sight like the Troy (which I am also using) can be sighted in at 50yds and you will be within 2.6" out to 225yds and within an 8" plate at 300yds.
Beyond that distance, I have a real difficult time even acquiring and identifying targets with my naked eyes, so I haven't had much need for a backup sight that is elevation adjustable.