A substantially panel system for a truck includes a middle portion, a clamping portion, a displacement portion, and a clamp. The middle portion has mounting features configured to rigidly receive accessories or accessory mounts. The clamping portion is disposed above the middle portion. The displacement portion is disposed between the middle portion and the clamping portion and defines a lateral offset of the middle portion from the clamping portion. The clamp pulls the clamping portion toward a lip of a bed rail of a sidewall of a truck bed, thereby coupling the panel system to the sidewall of the truck bed, without the middle or displacement portions laterally extending farther toward the lip of the bed rail than the clamping portion.