If you plan to have them powder coated, ok, my vote go to the black colour.
If you just want to paint them with regular stuff, keep 'em stock.
Ok now, the tailgate...don't get me wrong, it's your own project so you choose at the end...but I must admit that, for the very first time, I don't like your choice.
I really don't like this "locker door like" tailgate.
I'd prefer something more, how can I say, conventional. A rectangular shaped embossing with white lettering (reverse embossing would be very cool) in the center.
Something like this (sorry, I did it in a hurry...):
