Dry storage for sides of bed?

I have no need for a large storage box in the bed. That’s where the refreshment chest goes, anyhow. I’m looking for something that will fit in the sides of the bed basically where the bed is slightly raised on each side of the 900 S. These would be for basic tools, extra belt, plug kit, small compressor, mini jump box, etc. Lockable would be ideal, but not necessarily required.

Is there such an animal out there? If not, has anyone come up with something that will work? My first thought was ammo cans but the ones I have on hand are too wide which would interfere with the ice chest. I would prefer they were longer, anyway. The more of that raised area of the bed on each side that I can use, the better.

Any and all suggestions / ideas are welcome. Thanks in advance!