This Is what I do but it is not a recommendation for obvious reasons but it used to be the norm in some very good restaurants befor regulations set in.
I have a bout 3 dozen shell haves and have been using them for years in preparing
Bienville and Rockefeller oysters. The shells have been cleaned ( wire brush) with soap and water and bleach and then boiled in hot water. I let them air dry then place them in a zip lock bag and store in the freezer. Care is taken not to allow any adductor meat or food particles remain after storing. To remove the adductor meat and attachment spine I used a dremmel.