SharePoint 2010 Best Practice for collaboration with external companies

I have a SharePoint 2010 Enterprise farm where staff can access either outside or inside of the network.

I have been asked to provide out of network access for non-staff, those working for other companies of government agencies in a collaboration form. All of our data is on the SharePoint Enterprise farm running on a 2008 SQL.

Is there a way to set up a single SharePoint Foundation server that will pull and push data to the SharePoint Enterprise farm. This solution would need for staff to be able to log into either the Foundation side or the Enterprise side with their single AD account.

Thanks for the help.