There are no real alternatives. Glass has mostly the same bonding issues but is more expensive and heavier. Putting acrylic or glass panels in a steel frame dramatically reduces the probability of failure but you lose the wow factor of having a single sheet of transparent material.

I don't think any installation of this size can be truly safe. It has to be constructed in-situ being too large to transport so you would have to come up with some way of pressure testing the tank in-situ.