Can shipments be limited to only 100 Sales detail lines?

We have an issue where we are working with UPS Ship-Exec for shipments and have found they cannot handle a shipment that exceeds 100 detail lines. Is there a way to set up a threshold of how many lines can be added to a shipment at shipment creation so it will assign a new shipment number once the threshold is reached? Right now, we are catching during pick/pack confirm before we send to ship-Exec but that causes delays, and the pick slips are printed by shipment. Before I add a custom enhancement, I am looking if this