All I can say in regaurds to the sand is that Corydoras cats, are more durable than plants. I would NOT plant glosso in fine sand . . . If anything, a compromise could be made in using coral sand. I have it in my 20g-- the cories love it still, and my sagiteria spreads over it like crazy. Make sure you have enough light for carpeting plants.
My experience though, having some bare substrate in front CAN be effective in composition.
My experience though, having some bare substrate in front CAN be effective in composition.