clean/smudge filters on .zip/.tgz files

Various programs that I use ([Open|Libre]Office, Vym, etc) use a zipped/.tgz'ed file format, usually containing multiple (usually) plain-text files within.

I'm trying to figure out a way for git to treat these as virtual directories for purposes of merging/diffing.

Reading up on clean/smudge filters, it looks like they expect one file coming in and one file going out, rather than one file on one side and a directory-tree of files on the other side.

I tried creating my own pair of clean/smudge filters that would uncompress the files, but there's no good way put multiple files on stdout.

Has anybody else played with such a scheme for uncompressing files as they go into git and recompressing them as they come back out?

-tkc