Hi Kurtis,
I have a full length rack also, and towards the rear I had made up a lipped rectangle raised section that holds in place a rubber mat base (about the size of two door mats). You can throw up on top jerry cans, full water containers, cooler (esky) etc almost anything on to the rubber section, and once strapped down it doesn't slip and slide like everything else wants to when sitting on the mesh alone. Rubber never moves when nothing up top because the lip holds it neatly in place.
Here's my setup all powdercoated black ... Sorry but best pic I can put my hands on but hidden under that gas container on top is the rectangle base with the rubber mat insert.