Locate NextGEN gallery folder outside WP-content?

I have searched, but found no simple answer to this. WP novice here, so excuse me if this sounds dumb.

I am building a site that will contain a huge number of photos. Currently I backup using a facility on my host where I can zip the whole site (or partial site) and download. This is convenient and works fine, but I see a situation soon where it will become difficult due to the size of the …wp-content-galleries folder.

My current WP installation is (mysite)/public_html/mysubfolder/

If I could locate the Next GEN gallery folder in public_html then backing up mysubfolder would mean I didn’t have to include the photos every time.

I’m really not bothered about photo backups as I have all the descriptions, etc. loaded from IPTC fields, so restoring galleries is a cinch.

With my original installation of NextGEN, I left the default setting of wp-content/gallery/ for Gallery path, but if I wanted to locate it two above that, how would I enter that path? Is it possible? Or any other solution please?

I currently only have a few galleries and wouldn’t even mind re-uploading the whole lot. Thanks for any suggestions!

http://wordpress.org/extend/plugins/nextgen-gallery/