We've been going 4hrs for a good while now. I still would follow his cues and "feed on demand", but if we get to 4+ hrs without a BF, then I offer a BF regardless.
Does your LO show hungry cues at that point? Do you think you could start by stretching out the time very so slightly by 15mins before the next feed? - say, 3:15 for 3 days and then, if that was going ok, stretch it to 3:30 for another 3 days, etc Do you think that could be a goer?