Kit Item Functionality

We have a customer that orders a right-side and a left-side of an item together.  They require that we ship equal pairs of the right and left on any given shipment.  So if they order 10 of item X(Right) and 10 of item Y (Left), they don't care what quantity we ship in as long as the pairs are equal.  I proposed a PTO kit to keep the children in the correct pairings, but he sales staff doesn't think the customer will accept the change of ordering/invoicing a kit but receiving the separate items.

Any suggestions (other than manual ship set manipulation which is what we are doing now)?  Maybe a way to kit the item internally but order, ship and invoice the individuals?