"Screw down - don't screw up" - yes, pin migration is a very real issue. IF he ever takes it off-road (chum - chum)If you intend to keep swing out latches I would suggest if the holes for the lynch pins were vertical instead of horizontal potential 'walking' wouldn't be as big of concern?
Just wait till the pin migrates out and a swing out arm swings and hits the bed side when making a turn. Ask me how I know...