Can you set and listen from the entry point without bumping him if he chooses to roost there?
I'd start there the evening before about an hour before fly up and just listen. Listen for yelping, scratching, gobbling, anything that indicates where the birds are. They make quite a bit of noise flying up to roost and getting settled on the limb. If he's close to the entry point you should hear him fly up. It's not uncommon for a tom to separate from the hens just before flying up and roosters alone, so multiple birds flying up may not include the tom. A single bird flying up will more than likely be a tom.
If you dont hear him fly up, Id use a locator call. I have luck with an owl hooter and a coyote howler but stuck with the owl for the most part when back home hunting Easterns. I like the yote inbig side open country. Owls make a lot of racket, I've blown my guts out on the call before and not heard a peep and knew there were birds close by. I've also blown my guts out on it off and on for 10 or 15 minutes with no response, then give one more simple series just before getting in the truck and had a tom fire right back and everytime afterwards.
I'd do what I could to avoid walking under him, but as a last resort I'd consider it very early. I'd do everything I could to sound like a deer walking and would not use any sort of light.