What would be the best way to setup the plugin for my scenario

I've been beating my head against the wall trying to figure this one out.

Scenario: I have a site that needs membership levels for 3 different categories of members who will be able to access the backend for submitting content. And, I have one area which is protected "community" which includes forums, profiles, directory, etc.

This is what I've tried:
Setup the 3 categories for members.
Setup a category for "visitors" which allows the public to view the site, excluding protected content.
Setup a free subscription for all registered users who then get assigned an elevated membership level of "community"
Setup a URL Group to handle the "community" pages which is assigned to the member level "community".

Here's where I'm running into problems:
When the public visit the site, all is well.
But when a person signs up, they are assigned the "free" subscription and assigned the membership level of "community". The entire site ends up being unaccessible with the exception of the url group "community".

This is what I'm thinking:
If I don't setup a public level, then the entire site gets protected.
Once I do setup a public level, I should be able to create an URL group to add areas of restricted content on top of the visitor level. But the entire site is still blocked.

How should I be setting this up?

Thanks,
David