Android : Store App-specific Synced Data With A Contact?

I would like to store some app-specific data in the contacts db. Is it safe to stuff random things into the Contacts.Settings table? Will it affect the GUI? Does anybody have an example of doing that? It's not really clear to me if there's a proper mechanism for this, or if the settings table is reserved for the systems own use.

BTW my first attempt was to use an app specific database, but then users would uninstall the app, reinstall it later and wonder why it didn't work. My second attempt was to stuff the data into the JPEG headers but the sync process deletes them, presumably for security reasons. So if there's no way to store my things in the contacts db directly, I think I'm out of luck - I'll have to look at steganographically encoding the data into the raw pixels themselves!