I don't know the answer, but from the point of view of a webmaster who
gets support requests and doesn't have a windows system, it would be
very useful to already know where a person's python is supposed to
be, and thus good if the documentation said something along the
lines of:

If the user does not specify %LOCALAPPDATA% then it defaults to
<wherever that is> 

assuming there is such a default, of course.