Appreciate all the responses, guys.
My powder coat guy got hold of a bunch of stencils for the lettering, so he's going to give one post a shot. We'll see how it turns out. I'm worried about the 'sharpness' of the finish, as Gil mentioned. But if it fails, I'll just try the liquid paper option.
Love your vinyl letters too, Gil. Have several posts with them installed. But living in the US south, where it's 90F-plus and 95% humidity for almost half the year, the letters have a shelf life of about 3 or 4 years max. With 7 or 8 posts to 'maintain', something more permanent is needed in this climate.