Let's take a closer look at Rick's wonderful photo.
Focus on the second bent from the front (the one with the keg standing next to the frostbox). Note the diagonal attached to the front of the bent, and in particular where it crosses the front of the frostbox. Does the bottom look thinner? In other words, was the frostbox assembled
around the cross-brace, rather than the cross-brace being applied
over the frostbox?
Then look at the light spot right behind the keg. This appears to be an opposite diagonal on the far side of the bent. Note also that the end of it appears to be poking out from the end of the bottom plate of the bent (right next to the tin washbasin). If so, this cross-brace goes
through the frostbox, giving more credence to the frostbox being built around the braces.