One metal support in the center back was the original Boler
set-up, I believe. That said, seems like any of the other arrangements would work, too. Two on the left would likely give the best support (closest to center of trailer). Two side-by-side could also become an attachment point for bins, paper towel holder, etc...
If the support has been AWOL for a while, the roof may already have some sag. If that's the case you could post a question asking other Boler
owners to measure the distance from the front left corner of the upper cabinet straight down to the counter. I have read where others used a jack to apply pressure to the ceiling (gently!) to restore the original height when reinstalling the supports.
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