I disagree. The larger the tank, regardless of acrylic or glass, the greater the forces any uneveness exertys. Al;though you might be okay, understand that you are definitely stressing your tanks joints in a way that its not designed to handle.
I personally would drain it, then make it level. No guessing. Just doing it "right" is the way to go. Will it be OK? Probably. If it's level you will KNOW it is ok.
