I did it a few years ago
With my 15 month-old daughter (big for her age) and my husband. We used two GPUs and upgraded to lie-flat on the overnight EWR-Lisbon.
He slept well. She slept well. I did not since I had to scrunch into the remaining space at the end of my seat (she stretched out at the top). I am 5'6" and 120 so I could do it, but I was tired.
So it's doable if someone wants to take one for the team. :-)