I started working on them this week.
I dont think there is much force placed on the frame (unibody) most should be on the pinch seam so I just used 3/16 plate and 2 bolts per leg or 4 bolts per side. All the steal I am using for these is 3/16 but the 3/4x3/4 angle, for the pinch seam, is 1/8.
Here I have my mounting plates welded to the "legs" for the main bar.
I will update as I go along.