Thanks for the feedback, if you have any more pics of the fittings it would be appreciated. Also did you make the cross members on the bed panel out of the same ply or other .?
The cross members of the bed panel are 2”x1” ali box section sandwiched between tulip wood and or in places birch ply. If I did it again I’d use 2”x 3mm Ali flat bar. Bit like a flitch beam. Less weight and should still stop any deflection.
The riv nuts are hidden from view, but there are plenty of good places in the inner skin of the van to fit them.
Hope that helps