Registered just to help you out there buddy. So far all I've found to keep that tampering warning from popping up is to turn off steam sync, save the game, edit the save, then load it and go about your business. I haven't turned steam sync back on yet since I don't need it, but the tampering warning, once on, seems to stick. So if you can stomach starting a new game or reverting to an old save and editing it with steam sync off, that'll do ya.