My Journey, bought a step deck

Under your bunk, if you don't want to drill into the railing and install a locking bolt per pocket, or you could sliip a small box under the upper deck near the landing gear. You have options, just choose one.

 

If you mount a box on the side of trailer they seem to have a problem getting ripped off and high centered.
I put pipe pins on my old step and never used them.
Welded two pcs of L channel from bottom of beam to underside of pocket rail on a angle and just drop them down in. Made a pin with a flat piece of steel strap and dropped it down in a pocket so they would not bounce out. A lock or a bolt would secure it from theft.

 

I also have seen where they hung placard's between the step and landing leg.

 

Any room for a box on your truck?

 

When I drove for my old boss we ran a single 120gal tank on the driver side and had a 60” box under the bunk on the passenger side and it was wonderful. Had room for everything between that and the two big boxes on the trailer. I didn’t have dual tanks working there until the 2017 glider I got and then we had two big boxes and two small boxes on the trailer.

 

A box like that is always an option if you start running out of room and don’t mind fueling almost everyday. The bonus is you would always have a pile of showers on your card.