On Jan 22, 8:36*am, blueman wrote:
I bought some more "ess cleat" last night and it actually seems to be
about as stiff as 1/8" flat iron (note "drive cleat" was significantly
less stiff which is understandable since it has 2 (at most) layers vs
the 3 plus layers for ess cleat). I figure if I need more stiffness I
could even interdigitate two pieces of ess cleat to get an even more
ridgid band.

I will let you know how this works

If it's about as stiff as 1/8" flat steel, you're wasting your time.
Even 1/16"x1/2" angle aluminum will provide way more stiffening than
1/8" flat steel.

1/2" ain't gonna kill ya. Just round off the corners with an angle
grinder or belt sander and screw it on, either in an X pattern across
the panel that's bowing, or horizontally across the middle of the
panel, making sure to overlap the ends.