How can I create a Windows 8.1/10 user account that mirrors a guest account
Here's what I did on Windows 10 to provide a user login for some visiting guests: I created a new standard user named "anyone". Then I set the properties for the C drive to deny all permissions for "anyone". (I had to add "anyone" to the list.)
Setting those permissions did run for a while.
Now "anyone" can run programs, including the Chrome browser, which is all I cared about, but has no access to the C drive, so can't even list the folders there. "anyone" still has access to its own Document, Photos, Downloads, etc., but no way to get to them via the C drive.
This is pretty restrictive, which is what I wanted. It may be too restrictive for the case you described.