WCF Design with existing application

Question

I have an existing Asp.Net 2.0 application structured as SQL 2008 --> DAL --> BL --> WebForms. The application is only accessible internally on our Intranet.
We have recently decided to expose certain data to our customers that want the information.
I figured that WCF is the perfect solution for this however I am having a hard time understanding how it fits. The new WCF service obviously has to live on our external IIS so customers can access it and it needs to talk to our internal data store.
My first thought was to create a new WCF Library and reference my exisiting applications dlls so that I would have access to the BL and DAL. This seems a little silly to me strictly because of the rate of change of our internal application. We sometimes do 2-3 releases a week.

Then I thought what about bypassing my internal applications layers altogether and using LINQ.  So the service would be structured as External IIS WCF Service --> LINQ to SQL --> SQL 2008.
Is anything wrong with this approach? Considering that the structure of the data we are trying to expose is fairly static and little or no Business logic needs to act upon it. The service's only purpose is to expose very select and limited data to our customers.