I don't have anything beyond the usual advice. Keep your lights on the same schedule, let him sleep if that's what he wants. Offer some water every few days and record his weight. That should remain fairly stable through brumation.
UPDATE!
Smaug brumated for almost 4 months. He seemed so droopy for the two weeks following, I decided to take him to the vet and just as Drache613 predicted, he had parasites. I am currently treating him, with Panacure and flagyl. He seems to be doing well at day 3 into his treatment. He is head bobbing and running around again.
The vet said that during brumation a reptile’s immune system goes down due to the lack of nutrition, allowing parasites and bacteria to grow unabated.