I have a tub, which I consider to be large, recently bought used from a neighbor. It is a hexagon about 7’ across, made of thick fiberglass/plastics I guess. It seems solid, no cracks, I would like to keep it this way. I am intending install it above ground, to build a deck/support which sits under the rim, and lets the bottom set on the ground/sand/block. Is this the right way to go about it, what ratio should the rim support vs the base. And, how to calc and design to meet ideal ratio?