I like making the fender portion of the flatbed into storage compartments, preferably water tight, since I like to get muddy. I also like the idea of doing a hard tonneau
top for the middle portion as well. That way I have a flat surface for large items without losing storage space between the fender parts.
Not sure what you meant by factory rails. I might know once I take my bed off and see what I have to work with. If also like to look at other flatness in person and see what they did.
I also think I'll go with flush mount trailer lights or just keep the light bar I have since it has parking, breaking, turn signal as well as white backup lights.
I might end up not using the current roof rack. I want bed bars that I can put a CVT tent on, so even if I kept the current roof rack I would have to add bars anyway that would then be removed when I put the bed back on. Plus trying to configure the flatbed to also work with my current roof rack would be a hassle. I'd rather start fresh. I have some cool looking ideas for bed/roof bars.