Do I need center braces?

[arkmann]

With the angle iron I was referring to running it under the 2x4 across the length in the front to stiffen the span. You would have to make sure it was supported by the legs.

Same thing with adding another 2x4 just double them up in the front and screw them together to strengthen the span.
Effectively making the front beam across a 4x4
I would say either one would work.

I think this is the how I'll do it. One more 2x4 underneath the longer span supported by the legs. Should I add one for the width as well or just the length. 30" width.

 

[BIG-G]

The length should be enough.