I re-inforced the back side with some more two-part adhesive, sandwiching in the steel mesh on the sides between two layers of Ure-Weld:
After having some time to cool down, I have to admit that having to redo this thing might have been a blessing in disguise. It is noticably stronger than it was, and I have complete confidence in this thing now. It couldn't be any stronger even if it was one peice. The Ure-Weld really makes a nice hold.
