Preheat the oven to 350˚F. Cover the bottom of a 9 X 13-inch baking pan with aluminum foil, with extra foil on all sides. Then cover the foil with nonstick spray or softened butter.
Cook the diced bacon in a small non-stick skillet over medium heat until crisp. Drain on a paper towel-lined plate and set aside. Reserve 2 tablespoons drippings.
Whisk together flour, baking soda, cinnamon, and salt for the bars in a medium bowl; set aside.
Whisk together pumpkin puree, granulated sugar, 1/2 cup brown sugar, the egg, melted butter, bacon drippings and vanilla in a large bowl until well blended. Stir in the flour mixture and pecans and blend thoroughly with the wet ingredients.
Spread the pumpkin batter evenly into the prepared pan. Bake until a toothpick inserted into the center comes out clean, about 25-30 minutes. Let cool completely on a cooling rack before frosting.
Caramel Frosting
Combine and whisk together 2 cups brown sugar, 1/2 cup water and a pinch of salt in a large saucepan over high heat. Bring to a boil for 5 minutes, swirling occasionally to prevent scorching. Whisk in the cream and butter pieces. (NOTE: Mixture will bubble furiously.) Keep whisking. Boil for 2 minutes more.
Transfer caramel frosting to the bowl of a stand mixer with the whisk attachment. Whip on high speed until the sides of the bowl are cool to the touch and the caramel is thick, about 10 minutes, scraping down the sides of the bowl with a rubber spatula. Add the cream cheese, one cube at a time, until the frosting is smooth.
Using the foil, lift and remove the pumpkin cake from the baking pan. Carefully pull back the foil from the sides of the pumpkin cake. Use an offset cake spatula to spread the frosting over the cooled cake.
Sprinkle the reserved cooked bacon, pecans, and salt over the frosted cake.
With a sharp knife, cut the cake into 24 bars and serve.