in lew of .not in addition to.
abandon the underside of the frame rail altogether and mount a narrower skid inboard. the angles would/could mount to the inner frame rail for skid mounting and structural support. the top would be open . no longer need nutserts, be less material to manufacture and a couple less lb's too.
The aluminum plate also acts as a big structural gusset to the frame. On mine, when driving without out the skid and only the crossmember, I can feel how much more noodlely the Jeep is. Even on pavement.