So, I shouln't have crowed so quickly with delight after one success. That was the only success with that method. That gimmick included waiting outside of the sleeper's room, watching until the first signs of early waking, dashing in, nursing/soothing the child back to sleep before she woke up. This is not the solution I needed. I needed something that didn't require me to re-sleep her half way through each nap.
The good thing about that original dud was the idea of lurking outside the room right around the time of the early nap awakening. I used that strategy to see that Eloise was startling herself awake. She looks like I might look when I have falling dreams. This triggered me to remember that the nap strike began around when I decided she was too wiggly to swaddle any more. So, I've resumed a semi-swaddle technique that seems to make her feel safe and keep her from startling. Longer naps have been the joyful result.