Increasing Storage In A Limited Space

My storage compartment is 23 inches wide. That's enough room for 2 PCGS boxes with 5 inches to spare. My boxes are filling up and I'd like to take advantage of those extra inches.

PCGS boxes are 9 inches and hold 20 slabs -- there are no smaller options among their branded boxes. Poking around ebay, I found this box which holds 10 slabs in 4 inches. It would be perfect but I'm not sure I trust it. It's described only as "plastic", similar items on the 'bay ship from China, and the description for this one (although allegedly shipping from California) was clearly not written by a native English speaker. Functionally, it would work, but my concern is about the nature of the plastic -- might it contribute to any corrosion or other damage, perhaps by off-gassing? I have a few desiccant packs in my boxes so I'm not too worried about humidity.

Alternatively, I'm considering an Intercept box -- at least, replacing one PCGS box with Intercept because of the space restriction. Those hold 25 slabs in 12-1/2 inches, so I can get an extra 5 slabs (instead of 10). This wouldn't give as much additional storage and these boxes don't seem to have the divider rails so I can pull the slabs out easily -- they'd basically be jammed in. It's not like I pull them out to look at them often (they're in storage, after all), but it doesn't seem to optimize the space. I'm also not sure what kind of additional protection the Intercept boxes would give me. Do I need to smaller cardboard box inserts? There doesn't seem to be room for desiccant packs either, unless I store only 24 (or fewer) in the box, and that's starting to defeat the purpose of the upgrade.

What would you do? Are there other alternatives?