New tank 300 gallon

[Ograx]

Well I'm looking at upgrading from a 125 to a just under 300 gallon tank.

I have a few question to those out there who have built a tank this size.

My wanted measurements are 72x48x20

What kind of bracing do I need at the top of this tank so it doesn't burst ?

I need the drain and return from sump to be invisible and not on 1 of the sides of tank. ( Tank will be in middle or room with 360 view)

Any ideas or pics of something similar would be much appreciated.