Pin box hits bed rail

I don't believe you mentioned the clearance between the bed rails and the fiver. Since you have the ball socket behind the pin, you have already shortened the pin box by 4". I wonder if you lowered the ball so everything was more inside the bed, if it would give the pin box a little more room. I have a long pin box, have the adapter backwards, the Andersen ball at its lowest setting and it solved the issue I had of the back of the pin box hitting the bed sides with a regular Reese hitch. I still have 7-8" above the rails and am still a little nose high.