I get a lot of use out of mine.
One side has the 2x6 wood leveling blocks, some plywood base for the Hi-Lift and a collapsable grey water bag.
Other side has a small air compressor. Plus a good spot for things with fumes: small propane bottles, charcoal fire starter, dirty underwear.
Could also be a good hidey hole for contraband?
x2 on the ventilation. I added some bug screen to one of mine.