I always get to a high point where I can hear the best, well before dawn. I don't try to illicit a response but let the birds do there thing. If I can then get to within 200 to 100 yards of a gobbling bird I do that. If I can't, the next morning I'll get in the general area where I heard the birds. Then when they flydown I maintain that distance if the wind allows, following using my ears, I don't have to see them and undisturbed flock makes lots of noise, so I understand there travel routes to feeding areas once off the roost. Off course I am doing this once the gobblers start to hang around the groups of hens. I also go out midmorning and late afternoon and glass openings/open fields to varify birds in feeding areas. I do my utmost best to not let the birds know I am there and I try to understand how a typical turkey hunter would hunt and set up on the birds so I can do the opposite. See below.
A killer tactic on public ground or heavily hunted private ground, is, as you know, most hunters come off the road/parking area and go directly to the birds. Use the terrain to your advantage and come from the opposite direction and set up, and/or set up in the direction they like to go to feed and wait patiently. Call quietly, sparingly, like you too feel the pressure of the other hunters.
I have killed many birds that way on heavily hunted property, carefully working the ground "backwords". It works extremely well. Of course this is but one tactic for off the roost, there are so many tactics to use depending upon the phase the birds are in, the weather, time of day, etc.