I attended a VEX IQ Ringmaster Qualification Competition in Seoul a couple weeks ago and many of the robots were using a specialty plate (I wish I took a photo of them!!)
From what I can tell I think it was a 12x12 or a 16x16 plate that has got 4 triangle ‘cut-outs’ that reduce weight. It still has pin holes all around the perimeter, and along both diagonal struts.
I don’t know how to find this part to order it (and I have looked extensively)
Here is a quite merger of random beams that is kinda what I saw