Regarding tool box, try to use pre cut foam for keeping your tools in place or use "look in" hangers. Foam tool organizers by FoamFit Tools offers a range of pre cut foam for tools or even offers blank foam pad. Ziamatic Corp - Fire and Safety Equipment offers a wide range or Firefighther hanges devices.
The home depot kind of hangers normally loosen or the tools goes to any place inside your tool box. If this a "budget" project, just put your tools inside and include sound proof foam inside walls. IF you don't care about sound, no foam

Regarding POR-15, it seams to have rust converter and don't have UV protection.
Rust converter: turns rust to black like paint (even no rusted surfaces, i apply to my truck but i don't have photos at this moment (truck is in tranny shop up to friday)
UV protection: without it, the coat will gonna "destroy" (cracks, coat loosing parts). Withput coat, the metal surface will be unprotected and rust... A choise is to replace the coat every year, but it could be expensive.

If still want to keep bare metal, try do it in summer session or inside a paint cabinet (it depend on ambient moisture), and apply a lot or car clear coat (3 or more layers).