Maybe your friend was talking about this build?
I think either of you plans could work. I build a rimless 41gl that was
cut out an old 70 with 3/8" glass.
From what I've learned I'd tell you not to run more than 24" length without a brace if the glass is 1/4" @ 24" T. If you drop the height to 16 you would be safe with 3' between cross bracing.
I think for plants your 1st idea might be best. You could cut up the glass not being used for corner braces. Look at CrazyDaz's 200tank