Exchange 2013 and PF segregation

I run a multi-tenant Exchange environment (2007) and I'm putting together our migration plan to 2013. I looks like I can segregate my customers' public folders by creating multiple PF mailboxes (one per customer) and setting the "DefaultPublicFolderMailbox" property on the mailboxes.

Today, I have one PF database. To begin the migration, it looks like I'll need to run a command like:

New-PublicFolderMigrationRequest -SourceDatabase (Get-PublicFolderDatabase -Server e12-01.contoso.local) -CSVData (Get-Content FolderToMailbox.csv -Encoding Byte

What I wonder is, how do I migrate only the public folders from one customer at a time, from 2007 to 2013?

Thanks.