I only have a minute, but here's my thoughts--I'll try to touch base again later when I have more time. First of all, if he's tired, then don't worry right now about cutting out daytime sleep--sounds like he needs it and you don't want him to get overtired because that will probably make it worse.
So, he sleeps through the night without needing a feeding? Then do you think that he's possibly hungry when he wakes that early? Does he want to eat immediately? We had lots of early wakings like that, but often if I bf Savannah, then she would go back to sleep (with me in the spare bed, but it still meant we got more sleep and got to start the morning at a more normal hour, so I still did it for awhile).
If he's not hungry right away and you don't think that's the problem, then I would try the wake-to-sleep. I think its explained in Tracy's newest book--basically you jsut go in about 1 hour before they usually wake up (so for you, at 4:30) and jiggle them--not enough to wake them all the way up, but enough to disrupt their sleep--it is supposed to reset their clock and stop the waking. It may take 3 or so nights to see a change.
Just some thoughts. And if you do get him waking a little later, that will probably naturally help the daytime sleep to reduce because more time will be added to his nights. You'll probably be able to drop the 3rd nap soon.
Hang in there--we struggled with a lot of similar issues (and more, but I won't get you worried about that stuff until it happens!
~Kim