Modify the qualifying process of the Auto-Generate Invoices utility. Under normal operation an invoice is only generated if a customer has one or more qualifying items to be shipped. With this modification an invoice will be generated for all qualifying customers, regardless of whether or not any items appear on the invoice.
Update
V4.3.0.1 Updated to add a fuel surcharge to all invoices, even if the invoice contains no items.
12/6/04: If no items appear on the invoice, the "print invoice" option will be set to FALSE.