Search is your friend! There are several threads on this subject.
I was at the Ram rally held in 2013, at the Columbus IN. Cummins plant. One of the display trucks had a RAM box on display. In my humble opinion from my observation the RAM box pick-up bed would interfere with the pin box when you turned, unless you towed nose high. Another item I do not think the boxes can be open with the 5er attached if you only had 4" of clearance; it might work if there was 6" but no fifth wheel was attached to check this out.