Sitemaps in subdirectory when using an index?

Has any one been able to verify the validity of this sort of
configuration?

I want to have a sitemap index at:
http://www.example.com/sitemap_index.xml

This index will point to sitemap.xml.gz's at this sort of location:
http://www.example.com/sitemaps/sitemap.xml.gz
http://www.example.com/sitemaps/sitemap1.xml.gz
http://www.example.com/sitemaps/sitemap2.xml.gz
...etc.. (note the subdirectory)

I know that if ALL the sitemap files (including the index) were located
in a subdirectory then the sitemap would only be permitted to reference
URLs under the 'sitemaps' directory... But what if the index pointing
to them is at the root like above?

I would like this as my sitemap already requires over 50 files and I
dont want them cluttering up the root directory of my www directory.

Any help?
Jared-