Crustry you already answered my 2 questions or suggestions that I was going to offer.
And yes they are quite useful being that it is a low mount type and not one up on a stalk high above the bed has both advantages and disadvantages
Start with the advantages requires less mounting hardware, as the moment of inertia is closer to the base and frame of the truck , if so desired a tonneau cover can still be fitted to the bed. has a hydraulic jack for lifting like an engine hoist
Disadvantages has limited height for lifting larger taller materials. does not have an electric winch for lifting materials which can be an advantage given a certain point of view.