Here are two "Lolly Pop" type tang sights that look really simple and useful to me.

The first one is nothing more than a simple thumb screw from the hardware store with a hole drilled in it. It's screwed into a threaded hole in the tang and a knurled nut locks it in place. It's adjustable for elevation, but not windage.





The second one is more sophisticated. It's adjustable for both windage and elevation. It looks to be factory made, but wouldn't be that difficult to fabricate at home.