I have two of these (for cabin and load areas) in LGT, and one used as a reversing light:
White Rock Lights, YONEDA 4PODS Aluminum Housing IP68 Waterproof Pure White LED Rock Lights Underglow Fender Lights for Trucks, SUV, ATV, Offroad, Motorcycle : Amazon.co.uk: Automotive
I may well add a second as reversing light as I'm often reversing up a dark driveway, but in reality they give good light for all of £4 each.
They have curved rubber pads to mount easily to cage tube, and stainless bolts.