Hi Dave.
From experience, I think it's a waste of money having owt powder coated that's likely to see a hard life from stone chipping, powder coat's too hard n brittle, chips easier than paint, I avoid freshly resurfaced roads especially the wet tar/gravel bodge jobs.
Black rattle can Hammerite is what I've used, take a while to cure tho, hot air gun any metal first & very light coats, never re-coat unless it's touch dry, leave a good 6-8hrs between coats, too cold for paint to cure at this time of year unless you have a cupboard with a heater.
Hammerite looks better than powder coat imho & far cheaper, no need to press rubber damper bushes out like you'd probly need to do with powder coating.
If you're concerned about stone chip damage, you could wrap mounting crossbar with piece of pushbike inner tube & secure with cable ties, it'll never get chipped then or even some black exhaust wrap.
I've an OEM belly pan on my thou & a carbon fibre fender extender & a stainless rad guard, all 3 are a great combo that helps stop stone chips.
If I ever come across a freshly gravelled road, I hit the anchors & do a 180.
