Think of it like an invoicing database. Each event is much like an "invoice" where the packing list is then the "lineitems" for that list.
If you add a field to those event records for recording "confirmed" status, you can set up a report based on the packing list table that shows only those records for confirmed events in a given date range with summary fields computing totals for each type of equipment item.
That's a very generalized description, but it might give you a few ideas as to how to set this up. One key detail to think about is whether you choose to reserve each item on your packing list as a separate item or whether you list them as part of a group of identical items.