You sound like my old friend Crash, who wrote the CRM114 spam
filtering software. He has much more faith in a USB drive in his own
hands than in a remote source control system,
There's no reason you can't make a local copy of all zip files in a
local working copy, and check that in. I think you'd be in much better
shape if you bothered to unzip the first one, commit that to master,
make a tag, delete the local copy, unzip the second file locally,
commit *that* to master with all the changes, make a tag of *that,
etc., etc. in order to have tags with the relevant changes viewable.
It would make the release changes much more accessible.
There's also no technical reason you can't make a top level "tarballs"
directory, similar to branches and tags, and put your archive tarballs
there. It's not standard, but the flexibility is there.
Also, remember that Subversion has no reasonable "obliterate" option,
If you decide later that you don't really want bulky zip files, it's
very awkward to clear them from a source directory. If that source
directory is well defined and not part of the normal expected workflow
directories such as "trunk", "branches", and "tags", it will be safer
and easier to manage later.