How far up should I move it from the lowest point in order to avoid the problem that Sheldon discusses?
In the situation described it would be really a problem to remove the stem..
Since there needs to be someplace for the wedge,
to go, in order that it will loosen ,
once you tap on the end of the bolt , unscrewed to be proud above the Stem ..
so pragmatically... How about half an inch, ? ..
But, Not so high as the wedge is in the threaded portion of the Fork..,
it should remain in the part that is not thinned by cutting threads in it.