It is not clear to me whether you are using glass thickness calculators of which there are several reliable ones AFAIKnew. Part of the calc is the safety factor, to which the prior posters alluded to.
The only thing that matters is the water pressure on a piece of glass and the weakest link is the length x height pieces. The longer the unsupported length (no posts for instance) and the deeper the tank, the thicker the glass must be. The width of the tank is irrelevant. The pressure on the bottom is also irrelevant to the thickness of the vertical walls.
IDK if it is a good idea to have braces of tempered glass. Maybe commercial manufacturers do that, IDK. I imagine if you chip an edge, the brace would then instantly disintegrate, which may cause a cascading break on the vertical walls.
