Glad to have you with us a little more personally than just a reader of the forums. I hope you enjoy.
Big bucks are tough!!! I could repeat that 100 times. Even with the best advice you may never see this big dude again. And one more note my thoughts and or advice is by no means professional. you said you have already done some all dayers. Thats great. More time in the stand gives that buck more time to make a mistake. You hunt the wind. Also great. You seem to be also hunting their main funnel/travel area correct? Also great. But i wonder if their is some thick areas running alongside this funnel that maybe the big one is using. This way he is staying out of site and just checking for hot does with his nose. If there is any one thicket that you think he uses see how close you get to it and maybe try that. Also those farm hands might be able to help you out. What time they see him and how long ago it was. If it not the rut yet and lets just say they seen him yesterday at 2 pm I would try to hunt that spot the next day or 2. Maybe that field is part of his pattern route. If you notice a thicket he may be traveling through around your scrapes you found you may notice a light used trail in it. I think most bucks will check their scrapes somewhere downwind of it in the day time.
All your hunting spots sound good. You sound like you hunt smart. Im just trying to throw out some more ideas. You never know the bucks testosterone might get the best of him this year during the rut and he decide to travel right down that main funnel. Big bucks are tough but they still sometimes get a little careless during the mating season.
Last year I seen a big old buck during muzzleloader. around nov 5. i hunted this buck the rest of the year and never seen him again.
Time in the stand, cover your scent, hunt with the wind in your favor, and your in an area that a big buck roams. You got a good a shot at getting him as anybody. good luck and hang in there. youll get him.