Preheat oven to 350 F. (175 C.) Use a food processor to make 1½ cups of vanilla wafer crumbles. You can also place wafers in a ziplock bag and use a rolling pin to pulverize them.
In a mixing bowl, mix 6 tbsp. melted butter and 2 tbsp. white granulated sugar with crumbles until thoroughly combined. Pour the buttery crumbles into a tart tin with a removable bottom. Use a piece of cellophane to help you spread and press the crumbles evenly on the bottom of the tin and up the sides. Bake for 10 minutes and remove. Cool for 5 minutes, then refrigerate. Keep oven on.
Slice 1 cup strawberries and 1 cup rhubarb into small pieces. In a mixing bowl, combine with 1½ tbsp. minute tapioca, and 2 tbsp. sugar. Bake for 25 minutes.
While strawberry rhubarb bakes, add ½ cup heavy whipping cream and 1 tsp. cornstarch to food processor (you could also use a hand mixer in a mixing bowl, or standing mixer, but it may splash out of the bowl a bit). Process on a puree setting for about 15-20 seconds until the cream stops splashing inside.
Add whipped cream to a mixing bowl (or standing mixer with beaters) with 8 oz. softened cream cheese, 1 tsp. fresh lemon juice, ½ tsp. real vanilla extract, and ¼ cup sugar. Use a hand mixer on medium speed to thoroughly mix ingredients. About 20-30 seconds.
Remove tart crust from refrigerator. Spoon cheesecake mixture in, gently pressing it to the edges but not up the sides. Cover with cellophane and refrigerate.
Once strawberry rhubarb is done baking, remove and mix with a spoon to break up the fruit into a semi-smooth texture. Refrigerate for 2 hours. After 2 hours, gently spoon strawberry-rhubarb on top of the cheesecake, spreading it to the edges. Refrigerate tart for 8 hours before serving.