I did a test fill, but only about 1/4 of the way. There's 4 returns along the back and I didn't have bulkheads so I could only fill it up so much. Overnight there wasn't any leak. I'm going to get some bulkheads to plug up the returns, and give it a go at being full for a month while I build a stand
That being said, I plan on getting some quotes for a new bottom panel. The sides don't have any cracks. I figure if a new piece of glass isn't too much, I'll dabble with replacing the bottom.
If that fails, I'll spring for a new tank.