That's what I was about to say - put a poured concrete base under the building.
Like I said on the image below, mine is stuccoed brick (they used to stucco the bottom few feet of factories to protect the brick from erosion and people driving equipment into it), but you can make a similar base resembling stuccoed brick, CMUs, poured concrete, etc. I've seen this a lot with actual wood construction railroad buildings to protect the bottom for rot. That would give you more height.
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