Gift Registry and Local Pickup

I would like to enable a checkbox option for each gift registry labeled “Local Pickup of Gifts”.

This option would let users with access to the registry know that the gift registry recipient has chosen to pickup their gifts thereby waiving shipping costs.

On any gift registry where registrant has chosen Local Pickup of Gifts, a notice would appear stating, “The gift registrant(s) have chosen to pick-up the gifts purchased off their registry directly from , thereby waiving shipping costs for the purchasers.”

The shipping option at checkout would then display: “For pickup by Gift Registrant (must be approved)”.

Alternatively we could use a promotion to enable free shipping for each purchase, but this might get complicated!

What would be the best way to accomplish this enhancement/modification? Has anyone done anything similar?