...Can I just have pointers to the original debian root?
I'm not 100% certain, but I would guess that isn't good enough.

This doesn't mean your "simple" tarball/script has to contain the entire Debian archive. It just means that you must offer the full sources from the same location from which you offer your modified (cut-down) version. In a different tarball. So although it'll still take up space on your server, you at least wouldn't be forcing anyone to do a huge download.

At least this is how I understand it. I'm not a GPL expert by any stretch of the imagination.

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Tony Fabris