I think the old way of including the map with the Heavy Download (the EXE) would work fine...
We, the LAT Admins of the various servers, need a way to send our maps to like the bigfiles/thisserver folder of the downloads mirror...
So like, say the CC map changes, I can connect to
ftp://199.199.199.199/ or whatever as Classic and upload the map directly to the Classic Maps folder: the FTP account Classic only has access to the maps in that folder, and all players automatically get updated maps every time they rerun setup.exe.
Add in an automatic "There has been a new version released, would you like to run the setup program? [Yes] [No]" popup when you start Graal and the dates don't match up for current offline version/current online version....