It looks amazing but I've worked a lot with acrylic in the past and I wouldn't attempt that tank. With a glass tank, silicone will fill in the gaps where 2 sheets meet at an angle, with acrylic you have to cut them 100% perfect or the glue won't work as a proper seal. To do this you need specialized, big and expensive machines. I strongly recommend you leave out the two extra corners. What you could do instead is have it bent to the angle you want, same principle as a bow-front tank. That way you also reduce the risk of leaks.
Also bear in mind that corner tanks always have a dead spot in the far back corner which is then hard to reach and clean.
Just my 2c, I'd love to see you pull it of though