Artists' Painting Preparations

In dealing with larger work I have encountered a situation where additional rigidity on prepared panel is desire in working with gatorboard. In past work with architectural hollow-core doors I had noticed how lightweight, and yet solid they were. This was made possible by lamination and the design within them, some of them having no more than perpendicularly glued in cardboard pieces. Finishing it off, the backside of the door itself creates an integral I-beam geometric structure. Here is a design - the view from the backside - for a framework underlying prepared gatorboard on the exterior.

The supporting cross members are 3/8" plywood. Wooden blocks would be glued and nailed in after them to construct a strategic geometric structure. I might put thin underlayment-type plywood on the back, having not yet determined whether thin strips glued onto the back of these might  be the only other improvement necessary.