Use thick wall tubing- - - -.093" or thicker. Go all the way to the frame with the mountings. Big mounting plates and bolts are OK- - -welding is better.
Thank goodness I can't tell you that this method has worked because I have never been in a rollover in my 72 Blazer, but the above is what I installed about 30 years ago (8 bolts, not welded) and I do have high confidence.
