Nice cheap solution! If you have a welder and want something more permanent, you can make this for about $8 in scrap metal:
First off you need a grid panel. After doing some searching online this was the cheapest I could find. Lots of places wanted too much for shipping. 2x4 grid panel in black for $28 shipped. Perfect, don't even need to cut it down to size.
Black 2X4 Grid Panel - Bg-24 - Firefly Solutions
On to the brackets. Scrap pieces of 3/16" plate. Cut to size, welded and drilled to fit the existing grab handle bolt holes.
Ground the welds down cause I felt like being fancy
Bolted in
Mock fit
Panel is attached to the brackets using some u-bolt screw clamp thingamajiggers. I forget they're actual name at the moment