My one ton dually has a diamond plate flat bed on it, the org paint was crap and I simply took a wire wheel and buzzed it clean and then used rustoleum black by brush and it layed out perfect by time it dried. This was eight years ago and I haul wood, grain, motors, brush and its still in great shape today although I live where there is little humidity and it does sit inside most the time.
But for the time and low cost I dont know how I could be more pleased.
Let me look for a few pics.
Never mind the twisted axle parts in the pics but the oem junk paint was flaking off and wanted to fade to blue. The last pic was about a year ago and the RO has lasted great, I do put down a piece of plywood for motors or anything that will deep scratch or scuff things.