[bobbader]

I agree with Old Blue Oval here. Powder coating not the preferred process on body parts.

That said .............. whether powder coating OR painting, take the time, mount the boards, drill the holes BEFORE either process. In both cases, drilling the holes AFTER is just looking for a place for rust to start. You can touch-up the areas around the drilled holes, but, especially when the step plates are bolted on, water will find its way to pool in the proximity of the drilling and eventually rust will start in that location.

Now, if your desire for the step plates is not definite and you want to leave the decision until the boards and everything else are in place, you may have the situation stated above. Good luck whatever you do.