Having a consistent wake time will make a big difference for you. Consistency all around in the routine is key. Sounds like the 3.5 EASY is working, that's great.
If he's waking at 5am (or close) every single day then you can try wake to sleep for that, or you can resettle until it's time to start the day.
At his age it's completely normal to have a feed at 3am-ish. I wouldn't try and stop that, he likely genuinely needs it. You already know that you need to stop taking him to bed - you don't want to get in the cycle of trading one prop for another.
I doubt he's afraid of the dark - if he can sleep independently during the day he can do the same at night. He's not doing it because he's used to seeing you at certain times.
If you want to try a DF, it should be done between 10 and 11pm. It can take a week or so before you'd see results, so if you decide you want to give it a go keep that in mind.
And by the way, my DS is also very big for his age and I found that BECAUSE of that he needed the night feeds. They need the calories to support the growth - it makes no sense that they should not eat at night because they're big IMO. I'm glad that you're not willing to CIO even as hard as it is. You're right, it is cruel and it would only cause you more problems.
Hang in there, you're doing great and in a week you've already had huge improvement.
Just remember that it takes time to correct things, the same as it takes time to develop those habits.
