Hallelujah! I think it works!
For anybody who's interested, here are the missing steps:
7. Copy the Character.txt file from the Stats\Generated\Data folder to:
Your Installation Path\Divinity - Original Sin\Data\Public\My Mod\Stats\Generated\Data folder (you'll need to create the missing folders).
8. Open the Editor again and set your 'Mod Settings' to 'Startup Level = CharacterCreation' and 'MenuLevel = CharacterCreation' then save your changes.
I probably should have set these settings when I first created the module, but I forgot and the game gave me an error 'loading failed, level not found' message when I tried to start a new game. Setting the Mod settings fixed this.
Anyway, I hope that helps somebody.
