--IDEA--
(Unsure if this is possible)
Have the blind status reduce the view distance (The number of cells from the player at which objects will populate) instead of simply applying a dark overlay.
Example:
Assuming the sight radius is normally 18, blind might reduce the distance at which other players / monsters spawn their sprites from 18 cells to 12.
--WHY--
Now that grf editing is officially legal (for non mechanical purposes), it's fairly easy to include hard to prove mechanical edits into the grf files. If it's possible, making sight a more mechanically rigorous graphical debuff (object population) instead of just a dark graphical overlay would prevent a lot of temptations before they happen.
--BENEFITS--
The less things that need to work off of trust the better imo.