I'm working on a leveling system myself. Just wondering, but, where were you going to put your save file anyway? (Unless you don't need one.) Saves have to be locked up tight too.
I wouldn't worry so much about people cheating. In single player games, if someone cheats. They're only cheating themselves. If they've paid for a game, then moreso. (Though it's fine to cheat once you've played through it).