Oh for wanting a forklift. Would have been finished in 30 minutes or less. Finally resorted to typical Philippine methods and just picked it up, all 500 KG. Fortunately I had some foresight and reinforced the floor joists prior to laying the flooring. Been sitting in its crate for 2 years. Just too much "stuff" to get done.
I'll further reinforce the floor with 19mm marine plywood.
BTW, who else gets to use rough sawn mahogany as cribbing?