I'm not sure if my codebase would be suitable for you, it's rather specialized to client requirements (Online PDF publication permission system). It works off a system where the user pays for a subscriptions.
But if you feel like using it as a starting point, I can check it out for you. I'm not sure who the IP belongs to, us or the client. I also can't offer much int he way of support sorry.
If it were up to me, I'd give to you, but I gotta check sorry.
Be back to you before the weekend.