[EricH]

You could save a bit more weight without losing much strength by changing all the X patterns into pairs of triangles. Your machinist will also thank you for doing that; fewer cuts means fewer opportunities for something to go haywire and less time before you get the plate back.

Also, I might ramp up the plate thickness a bit around high-stress areas--mounting points and axle attachment areas--or put a flange on, like you would do for sheet metal.