I also think May is a great time! I'm going to be out of the country for about 3 weeks starting in a few weeks and would love to get in on Round 2 after than and after I've resettled into my regular life again.
Wow! I'm so impressed with all your diabolical planning to get those dang cats to walk on the mat! I'll add my "brilliant" to the chorus. I love that there is room for the scoop, too. I bet there's room enough in there for some kitty reading material, too. My own litter boxes are tucked away in such a manner that I used a plastic take-out container to put new litter in, so I don't have to lift the 30 pound bucket and hold it out at arms length. Maybe a similar solution would keep you from having to remove the box for that.