I like the way you set yours up better than I did on mine! I used mdf board and made braces for in the center and covered with carpet. I never even throught of just using two pieces like that and just cutting for the two rails. It is nice to be able to just lift it out and reinstall the 3rd row when needed, but like you I rarely use them. My purpose of creating the false floor was to allow my dog crate to sit flat when making long distance trips with the family. It just so happens that having the floor for everyday use is much more convenient than having the rails showing as well.
Joe