Which ever way you go, do the support thing, because someone will step on them or sit on them. Smoothie Fabrications probably has steel boards for your car if you are interested in steel, but glass would work just as well.

My running boards are the original steel, Easily repaired by a good metal man and able to withstand a 300 lb person without damage. Couple of years ago one took a beating from an errant SUV, and lived. Dinged, by not dead.