Organization/storage/securing inside my tonneau cover?

21 TRD Pro (short bed) with a Diamondback SE. Just picked this up and looking for the best ways to organize stuff securely in my bed. Molle panels? Attachments for the factory rail system (I did order the front rail since mine didn't have it)? The Diamonback attaches differently than some so some option might not work well.

Want it to be modular, but want to secure stuff like: recovery gear, CO2 tank, fire extinguisher, rotopax, luggage when traveling, tools, etc.

I may be better off to post on the Diamondback forum, but throwing out here first.

Thanks for any input.

-Bart