My goal was exactly the same has yours, keep the original look without loosing clearance with something really strong.
I use simple 1 1/4" sch 40 stainless steel pipe, with weld on short radius elbow. I perfectly match the OEM size of the board. I had a 3/16" or 1/4" plate bended, then using a grinder with a cutting disc and patience. You cannot see but even the fender bolt to the OEM step is there, i welded a SS bolt to the pipe. The big problem with it, is that once i was over welding it this thing was curved like s**t, even with patience and cooling. I brought them to my shop were i have a stainless steel specialist, we marked the slider and heated where we had marks to make it straight again, you can clearly see the heated place on the first picture.
Elbows are like 5-10$ each, then 1x 12' long pipe. I had some left over of 3/16" SS plate and i went to a local shop to get 1/8" checker plate. Obviously you don't buy a 1000$ 4'x8' SS 3/16" plate for this, you need to find a shop that is willing to cut and bend the slider, just have them do the piece longer then what you need and then cut it. Could easily be done in mild steel, i just had the left over ss plate and didn't want to keep touching up my sliders with paint
They would be wayyy too expensive to manufacture, lots of grinding and buffing. Doing a jig and mass producing them in mild steel could be reasonable, but still expensive. But i think the idea is the best i've seen yet.
If you decide to go stainless, you'll need obviously SS wire for the welder, appropriate gaz...don't try to drill SS without serious drill bits, don't drill dry but use cutting oil. Do not use grinding or buffing tools that has already been used in steel, you will contaminate your SS and rust will appear all over it. And yes they are 100% stainless, even the bolt holding them.
See all pictures here;
Stainless Steel Sliders
trust me, they already seen there share of rocks...