Special equipment: a 9-inch, deep pie dish
Preheat the oven to 350 degrees F.
Gently roll out the pie dough and line a 9-inch, deep pie dish with it. Trim the excess dough from the edges, and set aside.
Using an electric hand mixer, combine the sweet potatoes, 1/2 cup of the granulated sugar, the brown sugar, butter, 3 tablespoons of the rum, the vanilla, cinnamon, ginger, salt and eggs. Mix thoroughly. Add the coconut milk and continue to mix. Pour the filling into the pie crust and bake until a knife inserted in the center comes out clean, 35 to 45 minutes.
Place the pie on a rack to cool, about 2 hours.
Pour the cream in a bowl and whisk with an electric hand mixer. When it starts to thicken, add the remaining 3 tablespoons granulated sugar, the remaining 1 tablespoon rum and the orange zest. Whip until stiff peaks form. Serve the pie topped with whipped cream.