Puree enough cantaloupe to make 6 cups cantaloupe juice. Transfer juice to a large pot and bring to a boil over high heat. Reduce heat to medium and continue to simmer until juice has reduced to 1 cup, about 40-45 minutes. Remove from heat and let cool slightly.

While cantaloupe juice is reducing, prepare the crust. Combine vanilla wafer crumbs with melted butter until well combined. Press crumb mixture into the bottom of the prepared baking dish to create one even layer. Transfer to the freezer and chill for 30 minutes.

Combine cold water and gelatin powder, stirring until the powder dissolves. In the bowl of a stand mixer, combine 8 ounces cream cheese and ¾ cup powdered sugar for the melon filling. Beat until well combined. Add reduced cantaloupe juice, stirring to combine.

Microwave the gelatin water mixture for 10 seconds or until the gelatin melts. While the mixer is running on low speed, slowly add the gelatin mixture, mixing until fully combined. Transfer melon filling to a bowl and let chill in the fridge for 1 hour, covered.

Make cream cheese filling. Beat together cream cheese with powdered sugar and vanilla in the bowl of a stand mixer until smooth. Fold in whipped cream until fully incorporated. Remove crust from the freezer and spread cream cheese filling an even layer. Return to the fridge to chill.

Finish the melon filling. Beat the filling in the bowl of a stand mixer to loosen. Add ½ cup whipped cream and beat until well combined. Fold in the remaining 1 ½ cups whipped cream until fully incorporated. Spread melon filling on top of cream cheese filling in an even layer. Chill melon creamsicle bars for at least 6 hours or overnight. Slice and serve.