Preheat the oven to 350 degrees. Spray a 9-inch pie pan with cooking spray.
In a medium mixing bowl, mash half of 1 banana. Add 2 cups cookie crumbs and melted butter and mix well. Press the mixture firmly and evenly into the prepared pie pan, making sure to go up the sides of the pan. Bake for 10 minutes, then let cool completely.
In an electric mixer, preferably fitted with a paddle attachment, beat the cream cheese with the brown sugar until smooth. In a clean mixing bowl with a whisk attachment, beat the cream, rum, and vanilla until stiff peaks form. Stir one-third of this mixture into the cream cheese mixture, then fold in the rest.
Slice the remaining 3 ½ bananas and fold into the filling. Spoon the mixture into the cooled pie crust, sprinkle with the remaining 2 tablespoons cookie crumbs, cover loosely with plastic wrap, and refrigerate for at least 4 hours or up to a couple days ahead.