Would you mind sharing in better detail Rodney what your intentions are?
To me, cargo racks can be
* things you attach to your hitch
* cargo area dividers that run, say, at the height of the rear tub lip, that separate the contents below from prying eyes, sometimes provide a shelf above upon which to place additional items, and sometimes lock
* cargo dividers that run at different heights and sometimes, with the rear seats down, can transform into sleeping platforms.
* complex systems that feature slide out drawers, some of which provide essentials like cooking supplies for the Overlander.
...and in these categories there's often DIY and purchaseable implementations.
Mine's a DIY that can convert into a sleeping platform, with the GPCA cover linked above on this thread physically on top of it. Accordingly, my GPCA cover can hold whatever the wood below can.