I would try the following

Instead of creating a dynamic table within the select statement, declare a variable table ...

declare @a TABLE ( shipment datatype, carton_no_count int, Unscanned_Cart...

The automation and flexibility of this backup strategy appears safe.  I, however, would be concerned with the fact that it never does an incremental backup, which is the only way...

I can actually use a case, which is something that I should have seen earlier.  It will not be very elegant, since the cast is in the where clause multiple...