I have an 'in between' scenario. Paint it with a good primer like rustoleum rusty metal primer for the protection we need, and get out the brush. Finish coat on this bed is Regal red rustoleum enamel mixed with flat white rustoleum to make it a dull faded red, then some flat black to dull it some more. It cost about 50 bucks. I did paint it black with a rattle can after the primer and then buffed through the finish coat with a hunk of burlap to match the original finish of the faded cab. As you saw in my earlier post hauling a trailer, this 38 tonner was a working truck. I just couldn't stand the rotten home made bed that was on it when I got it. I found the 8' express bed as a utility trailer beside a house down in Seattle.. It was a metalic blue when I hauled it home, so I did my not expensive 'fauxtina' to it. This was 20 years ago. Wire wheel it, sand it, prime it, paint it, then buff it out. If it gets a big ol scrape, go find the coffee can you mixed it in, break off the layer of scum and brush on another coat where it needs it.....
'92 F350 4x4 dual wheel flatbed truck. 7.3IDI, 5 sp man tran. '59 F350 nine foot flareside with cummins 6AT, '47 2 ton stake with 8rt, '47 tonner panel, 47 tonner pickup,'46 tonner cab/chassis, 47 1/2 ton pickup,'46 1/2 ton panel. Antique one lung flywheel engines.