Well, not quite on target, but... Some years ago, I built a deck.
Because of where it was, needed to be just off the ground maybe 10". I
put 4x4 posts on 4' centers. Then galvanized hangers and 2x8 stringers
to make 2' x 4' grids. Then decked over with 2x6. All treated timber.
Posts were 36" in ground on concrete pads (local code requirement). A
few years later, I put a hot tub on it - pretty decent size - to hold
4-5 people. Held about 350 gallons, IIRC. Deck was maybe 5x the area
of the hot tub. Worked just fine. Clearance under the deck was maybe
4" at one end, and 2" at other end, due to grading. Rabbits loved it.
Would drive my Golden Retriever nuts, as he could hear/smell the
bunnies, but couldn't get to them.