Ok so here’s the final update. Hooked up to get measurements today. After moving the pin box I ended up with 8 1/2 inches between the top rails and the camper. That gave me about 3/4” clearance with my tool box. Not enough in my mind. So I put the pin box back to where it was and made the adjustment to the hitch and also decided to put the new slider in the work truck and, move it from truck to truck if needed.
A tip for anyone moving the pin box. Pull all bolts except the two lower ones in the back, leave one in the front as well. I then pushed up and supported the front of the box with my shoulder and removed the front bolt. Pushed the box up further and was able to put a couple of landscaping spikes in the upper holes to support the front. I then was able to push up on the back ,pull the bolts and, put them back in the lower holes of the original position. Once they were in I went back to the front and did the same thing there. Total of about 20 minutes by myself.