Hi I would try the dreem feed for a week and see how you get on. (We found when ds was on a 4hr routine he wasn't hungry enough for the dream feed. He would drink an oz and still wake again later. So not only did we have to stay up late but we had to wake in the middle of the night.)But not all babies are the same so it might work for you so do try it first, If that doesn't help and he still wakes at 4am I would try watering down the feed. I got the Idea from a sticky/post on nightwakings forum.
We tried it with DS it's the only thing that sends him back to sleep untill morning and it doesn't ruin his morning appetite. You can start eg. if he drinks 5oz usually, offer 5oz water and 4 scoops of formula (or the amount of formula to make 4oz milk) try this for 2 nights. Then if he's happy reduce it again (the formula not the amount of water) by another oz. You should see that he will start to drink more in the morning.
Then you will have two choices, 1-find a happy medium were he still drinks his morning bottle and his night time one and continue offering it to him .
2-keep reducing the milk and probably by the time you get to 2oz of milk he should probably stop waking all together.
If he wakes after two hours and is hungry you will have to increase the amount of milk again by 1 oz the next night, so he is content. This didn't happen with us though, it was the only method which worked for us and didn't encourage night wakings or throw off our morning routine.
Hope this was of some help
Natalie x