Since the cats are not at all thrown off by the litter being in the bathroom, I decided that today I would start raising it up. The website I've been following suggests raising the litter box two inches at a time, but I really didn't think they would be all that confused if I just raised it right up to the level of the toilet. (See today's photo. The cardboard box in front is supposed to be a step stool.)
The cats have no problem using the box at this level, so if I could, I would move onto the next step tomorrow. (At this point I am so convinced this is going to succeed that I am surprised the cats are not already using the toilet.)
However, we decided to splurge on the CitiKitty contraption and it won't be here for a few days. Also, J pointed out that we are having a Superbowl party this weekend and so maybe we should wait until after that before doing anything funky to our toilet. But we'll see. If the CityKitty thing comes really quickly, I might at least start getting the cats used to it even if during the party we put a litter box in the bedroom so the cats have a place to hide and poop in peace.