Can't say I've seen that, buds customs do something that is fits inside the sports bar but runs most of the length of the tub. I've built my own which is on Jaydo's rig now which was basically the same. How much weight for you want it to hold? You could just bend up some mesh similar to rhino rack cage with some 25mm box or tube around the top and stauff clamp it in the corners. Or nusert to the sports bar or better yet make some brackets that utilise the existing bolts for the sports bar
It's not going to hold much weight, just maybe maxtrax, jack, shovel and the like.
i was just going to make up some brackets and use nutserts, buy a tray/cage if i can find one, or make one. Just wanted to see if anyone else had done something similar first