Tank possible with 2 bottom panes side by side?

[lastlight]

I won't answer that because it makes this appear to be more than an innocent question (yes but it's more restrictive than my door to the basement currently).

So long as the panes are fully supported and they would be with the foam I don't think there are any forces that would make this un-doable. All the glass is pressed down evenly into the foam. Sides would have the same forces they ever would have. Nice wide brace to seal them and presto.