I appreciate the suggestions, some of which I'd researched beforehand. However, I have to put all this on hold; it seems UPS did a number and cracked the slate bottom. This has a created a seam on the inside bottom that runs the entire width of the tank and another on the outside bottom of the tank, near the middle support, which the far more troubling of the two. Though the cracks do not appear to penetrate the depth of the slate, I'm not taking my chances on this thing springing a leak in my office. Now I'm fully disgusted.
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What people usually do with a cracked slate is to just put a piece of glass over it.
In your case, if you really wanted to move forward, take out the cracked glass, remove the sealant with a heatgun and then silicone in a new piece. Then put a piece over the slate and silicone that to the other four pieces. Silicone won't stick to the slate but it will stick to the glass. You get a silicone sealed tank, just like a new one but with a stainless steel frame. Best of both worlds.