If you don't find anything I have a 10 gal (I think) with a crack in one of the corners you can have. I was going to use it for redoing my sump (I bought an eshopps instead). I am pretty sure the glass is 1/4 thick.
Thank you so much for the offer @Jeeper! I will certainly keep that in mind as I go out searching this weekend for parts that might work.