could there be a modification to the graphic (assuming it IS a graphic) that shows the areas Link can't walk on, but also shows the tile underneath? like, maybe instead of a solid square, there could be a box with a transparent center, or a half box, or something
this would help with setting transparent non-walkable combos (on layers) over tiles you don't want Link to walk on, like if you have a bush or something, and want/need Link to walk over the undercombo to move to the next screen... maybe an example quest would explain it better?