Travel18,
I have been having a cargo bed modified to have fold down sides (like tailgates on each sideo of the bed) to access storage compartments that have been created on each side of both wheel wells.
I made Molle racks out of 1-1/2 x 1-1/2, 48" x 120" x 0.135" mesh which I cut to fit. Then I had them powder coated.
They are plenty sturdy but not mounted yet. Unfortunately, this project has dragged on for over 3 years - the body guy I am using, uses the cargo bed job as fill in work and he keeps pushing it aside. It is almost done however.
I plan to mount the racks to L channel using appropriate L-Channel hardware. The L-channel will be attached to the back wall of the storage compartments.