I think we may have done it, folks! While Ben seems totally fine using the toilet whenever I remove the tray, Desmond still acts like a sad little kitty until I put it back. Today when we came home from work, I needed to clean the tray, so I tried to get him to use the toilet without it. When he cried, I put the tray back on with no litter in it. After a little hesitation, and a lot of coaxing, he finally used it! Ahhhh so proud! Are we litter-free? Maybe! Still have a ways to go getting him used to just using the white part and then using the actual toilet seat, but eliminating litter from the equation is pretty awesome.