I'd make or have made a matching wooden frame the same width of the bed with rubber on the bottom and sides that the cooler would just fit inside of. Better yet, have the sides of the frame adjustable so they would push against the sides of the box. No drilling required.

John

~ J Lucas
2006 GMC Envoy 4.2 I6
2023 Ram 2500/Cumins 6.7 I6
2010 Jeep Grand Cherokee (Wife’s)
2002 Silverado 2500 Gas 6.0
1941 Chevy 1/2-Ton
1942 Chevy 1.5-Ton SWB
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