[dsraven]

not sure where you are but where I am you need a light for the lic plate. back of cab would suck for that. could be integrated into the cooler if you don't mind chopping that up. I could see a cop giving you a hard time if the cooler isn't part of the truck, that is to say, bolted down.
a high mount brake light is something to think about. maybe save your neck and truck one day. with everybody being a distracted driver these days you need to make yourself visible.
firefighter, go to rear ender wrecks all the time. neck injuries common. it would also be a shame to bust up a quality ride as well.