Night one went better than expected. Sam woke at about 2:10 just like I expected. I took him to the toilet just to make sure that the need to pee didn't factor into any future night wakings. I put him back in his bed and repeated the routine. He cried and called for me. He pulled on the door. Then he tried the "naughty" stuff again, flicking the light switch and throwing a few toys. After about 10 minutes he climbed into bed and whimpered a bit. He switched to stimmy noises and hummed to himself for the next 20 minutes. At that point he let out one last "mama, mama" and then fell asleep. He slept for the rest of the night and didn't get up until just before 7am (late for him). I was very pleased. I was, of course, sad to make him cry and as penance I sat outside his door and listened to him long after I needed to. I was happy to see that he was in better spirits after a pretty good night's sleep (compared to what he has been getting lately).
Tonight, night 2, he cried again but for only 10 minutes and then he went right to sleep. I suspect we will repeat in the middle of the night but it seems the idea is sinking in. The possiblity of a full night of sleep for everyone soon is growing.