I finally fitted a mesh floor to the top of the trailer. It will be useful for carrying extra gear when needed. We carry our Portaloo on the top, plus our daughters tent when she comes with us. It will also be useful for carrying firewood we collect on the road.
I had two panels made up with diamond mesh with a frame. I then held it in place with aluminium angle ate each end, which is riveted in place.
The mesh panels have added some weight to the floor, which makes it slightly heavier to lift. We will need to look at increasing the strut pressures to compensate.