Looks spiffy, but I can't imagine why you decided to implement a lightening pattern that uses 4-sided elements.
A municipal truss bridge with 3-sided elements (triangles)
A municipal truss bridge with 4-sided elements (rhombuses)
The difference is that the individual members of the triangle truss are loaded only in tension and compression, while in the rhombus truss they're also loaded in bending. This additional loading means that each member of the truss must be MUCH stiffer.
Given the thickness of your chassis plates shown in the photo, my gut says the bending strength is acceptable here. But did you perhaps do any FEA on these plates to justify your decision?