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As part of a mid-ship water tank replacement I pulled the floorboard under the table to see how much storage was hidden. I was amazed at all that deep virgin space!
The table pedestal extends down into the space so the table can be lowered. There is a large additional 3/4 plywood backing plate screwed to the floor to provide additional support. This backing covers the entire surface area of the middle compartment.
I was concerned with how stable the floor would be if an access panel was cut, but decided the backing plate was so large a portion of it could be safely removed.