I am actually dealing with a similar issue, except my son only half wakes up at about 4, and is this way until 8-8:30 AM! He is 2 3/4 and still nursing, so that means he wants "nummies" every half hour or hour in this time, which means even less sleep for me. I have started cutting out his nap whenever possible...keeping him busy with outings to indoor/outdoor parks, running errands, walking our dog, etc. Then he comes home and unwinds with his toys while I make dinner. On these glorious days he is in bed by no later than 8:30, and sleeps until about 7 quite steadily (although he, too, has never been what one would call a solid sleeper!). Problem is that when we are home for most the day, he wants to nap, and if I try and with hold it at home, he ends up sleeping from 5-7 and being up until 11 or midnight. I am not giving very much advice here, but trying to share my experience in hopes we could maybe learn from one another-or at least feel the empathetic love of parents going through similar difficulties!
My main point is that the nap removal can help, but you would have to do so in a consistent manner if your son is as much like mine as he sounds in his sleep habits....and even then he might still wake up. My mom says I was the same way, adn that by the end of my 3rd year I was sleeping all night peacefully...so maybe it soon will be true for our children?
I am asking out loud that this will happen!! Best of luck to you as well!