H.A.
Don't know if it's much help, but I remember laying down with my DS during naps for, well, until he didn't need me to anymore. We would lay down and when he fell asleep, I would slink out of the room. I would also sometimes pack up some snacks for myself and a couple magazines and we would go for a drive. After he fell asleep, I would head to the park and park in a shady spot and let him sleep.