The challenge Idea - log caches 1, 2, 5 10, 15 and 20 km (Within a margin of error) from the cachers home location. Looking at the documentation, there is no access to the cachers home location. Is there a way to do this, despite no home location data?
If you look at the READ FIRST thread in the Checker Requests forum, you'll see
What a checker can not do
* The checkers does not have access to the user's home coordinates. Challenges are not allowed to be based upon them either, and haven't been allowed to for several years. This is a matter of integrity.