It was kind of a pita but I just fished bolts through and pointed them downward... for the one that's at the gas tank skid, I had to cut a window in the "frame."
I think if the threads are inside of the frame rail they are more likely to corrode and seize up. Mine were seized and I had to cut most of the bolt heads off to get the strips out. When the bolts are pointed down, and the threads outside of the frame rail, you can hose them off, and hit them with WD-40 etc. Although.. using the nut strip probably does make the hitch mounting surface stronger.. I just used big ass washers..