While I can't provide a more workable solution than the one you've already described, I use a PowerMac G4 with OS X Tiger that acts as a file server and backup for my LC III, which I consider to be my main 'classic' machine. Perhaps that's something you might consider? With an updated Open Transport and AppleShare, AppleTalk works extremely well between the two machines. The beauty is that my newest Mac with OS X Yosemite can see all of the PowerMac files, meaning that the PowerMac acts as a link between the new and the old(er). =)