D.S.
How about trying to get some headphones and let him listen to music that may be enough of a distraction and also calm him down to go to sleep on his own. My mother never put her foot down with my brother so he slept in a sleeping bag on the floor in my room until I was 16 and I put my foot down. I wanted my privacy. I think at his age you need to be firm with him otherwise he will continue to depend on you for sleeping. As far as him taking long to fall asleep without you I wouldn't let that concern me let him stay awake as long as he stays in bed. Eventually he will be tired enough and go to sleep on his own. Good luck!!