Honestly, I would not make a big deal about this. :)
Everyone gets stuck in the idea that children MUST do this or that, but really, unless you can actually see a significant difference in your son with a nap versus without, let him stay awake.
Instead of "NAP" time, create quiet time. Learning how to play quietly is also important. Having time to one's self is important, too. And, lets face it, Nap-time is just as much for Mom if--not more--because we realize quiet time is important for US.
Now, some people just tell their children to be in their rooms for a certain length of time. I have done that, too. I have, with older children, told them they could play as long as they wanted but that they couldn't come out of the bedroom until they've been asleep for a long time. (I said long time because they were little and didn't know how to tell time, PLUS they often tried to pretend sleep)
I'm not saying to let your children lead you by the nose, but, realizing your child's needs are different (even when yours are the same)is a good thing--and important thing, and allowing for changes while fostering growth and keeping your boundaries is wise.
It'll all work out...