I'm making the stand for my new cage out of grids as well. I'd recommend that you go ahead and make the stand part 5 grids wide if you want a 2X5 eventually. My 2X5 C&C on a grid stand takes 51 cubes (I think), but I'm building it so there are 5 cubbies under the cage to store supplies in and save some space in our family room. The basic 2X5 cage takes 14 grids. The base has a top and bottom 2 grid by 5 grid panels, a back that is 1 grid by 5 grids, and left to right as sides and 4 seperators to make the cubbies are 6 1 grid by 2 grid panels. It's still a work in progress, but I'll post pictures ASAP. If you want to PM me, I'll see if I can send some drawings as an attachment. Did I mention that I'm making a plywood base with wheels to set the whole assembly on, so I can move it when I need to vacuum or for cleaning the cage? Yeah, I'm a dork, but this will be my first C&C cage, and probably my only for a while, and I had a lot of specs when I started planning.
Hope some of that rambling helped you!