C.M.
5 am is very early to be up for him so it's understandable that he's still tired. I'd say you maybe should let him take 2 naps if he still needs it. My daughter dropped her 1 nap (only at home on weekends) when she was 2 and has always had a hard time napping. Even when she did it was only 1/2-1 hour. I do not think you should expect him to be napping for 3-4 hours, but maybe two naps of 1-1.5 hours each. Why not try it for a day and see how it goes? You could always put him down early if he doesn't take a 2nd nap and see what time he gets up!