Combine egg yolks, 1/2 cup sugar, and salt in top of a double boiler; mix well. Gradually add milk, stirring constantly. Bring water in bottom of double boiler to a boil. Cook, stirring constantly, until mixture thickens. Soften gelatin in cold water; add to hot mixture, stirring well. Cool. Add bourbon and 1 tablespoon rum. Chill until mixture begins to thicken.
Beat egg whites (at room temperature) until foamy. Gradually add remaining 1/2 cup sugar, 1 tablespoon at a time, beating until stiff peaks form. Fold egg whites into cooled gelatin mixture. Pour filling into pastry shell. Chill.
Beat whipping cream until soft peaks form. Gradually add remaining 1 tablespoon rum, beating well. Serve pie with whipped cream.