Preheat oven to 350 degrees F. Coat a 9 x 13 baking pan with nonstick spray.
Cook bacon in a sauté pan over medium heat until crisp; drain on a paper towel lined plate and set aside. Reserve two tablespoons drippings.
Whisk together flour, baking soda, cinnamon and table salt for the bars in a medium bowl; set aside.
Whisk together pumpkin puree, granulated sugar, 1/2 cup brown sugar, egg, melted butter, bacon drippings and vanilla in a large bowl until well blended. Stir in flour mixture and pecans.
Spread pumpkin batter evenly into prepared pan; bake until a toothpick inserted into the center comes out clean, about 20 minutes. Let cool completely before frosting.
Boil 2 cups brown sugar, water and a pinch of salt for the frosting in a large saucepan over high heat, 5 minutes, swirling occasionally to prevent scorching. Whisk in cream and butter pieces. (Mixture will bubble furiously; keep whisking.) Boil 2 minutes more.
Transfer caramel to the bowl of a stand mixer; whip on high speed until sides of bowl are cool to the touch and caramel is thick, 10-minutes, scraping down sides of bowl as needed. Add cream cheese, 1 cube at a time, until frosting is smooth.