Summarized Invoice by both Item and Shipment

We are looking at going to serialized items.  However, one of the concerns that we have is the impact to invoicing.  Since with serialized items you can only ship a quantity of 1, invoices become long and complicated.  I am testing summarized invoicing (Putting a 1 in the Item Summary under the Print section of the Invoicing Processing options).  This does seem to get me part way to where we want to be in that it is summarizing the items based on the item number.  But, if there are multiple shipments to a customer on a day (which is very