I used 25mm box steel for a frame then had a sheet of 2.5mm ally checkerplate folded to fit the shape. also had the frame gal dipped prior to sheeting it. it was a cruiser tray 6' x 8'.8" so i had to hunt around for a larger than normal sheet. i think it was 1550mm X 3000mm.
then attached it with Sikaflex and blind rivets. if you weld a pair of racks onto the top of your frame then you may be able to get away with a couple of smaller sheets. i used the big one cos i wanted no joins.
4 bolts and it came off, still needed it as a ute occaisonally.
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