Wanted to show it is possible for you to have even a larger toolbox with a back rack and still have a tonneau cover also. I didn't use the back brace that
World's Best Tonneau Covers, Truck Bed Covers and Hard Tonneau Covers Including Tool Boxes for Ford, Chevy, GMC, Ram and Toyota
Access® - Tool Box Edition Soft Roll Up Tonneau Cover
ACCESS Toolbox Tonneau Cover | Tool Box Truck Bed Covers