Have you tried the 'not let him be up for more than two hours' thing? He may be getting a little old for it, but that helped us consolidate naps more (turn a couple of those 30 min naps into one longer one). With my daughter, sometimes she will actually be very tired and won't really show it; she'll actually get more active. She's been that way since she was really small.
So, if he wakes up at 7, by around 8:30 or even 9, start trying to get him to sleep a little, do sleepy things with him even if he doesn't seem tired (songs, read stories). I used to wear my daughter in a sling or backpack and do housework (bore her to sleep).
This may not work for you, if he really truly isn't tired, but it helped us establish pretty consistent naps. We went to a mid-morning nap and then an afternoon nap around this age, I think.