The square check parts are not a good idea. You would square your axis and then have to move it to get them out. Just take a minute to measure them with a tape measure and you will see how easy it is.
I would still raise your material up as high as possible, you will see a huge difference in rigidity. For every half the length of your Z is 2 times the rigidity. Biggest possible upgrade is getting the material as close as possible to the z axis as high as it will go.