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I’d switch to feeding him in the evening. To make the transition, give him about half a meal in the AM, then all he wants at his new feeding time that PM. The next AM, he gets nothing. Expect him to continue to get you up for 2-3 days in the AM, but only let him out to potty and don’t give him anything to eat (not even a biscuit), then go right back to bed.

Yes, you absolutely have to maintain control over his eating schedule. These dogs are incredibly smart and will test you, especially as teenagers. Dogs generally don't really want to be in charge (dominant) over you and every other creature in the household. Dogs just always do what they find reinforcing - what makes them feel good, what they enjoy, what they get rewarded for. They repeat what works in their favor and abandon doing things that work against their desires. He awakes, he's a bit hungry, so he tries to get breakfast. If you ever give into this, you'll reinforce that it's possible to get you to give him food at 4:00am and his natural persistence (we have bred temperament quality into hunting dogs) will kick in. He'll persist and persist and persist at begging for food at 4:00am until he eventually wears you down and wins. So stick to your guns, completely ignore his demands, go back to bed and he'll give it up.