Short of taking photos and posting them, I can't tell you for sure with that description. As with any animal, your gonna see some variation depending on health and diet.
As to where to set up, you don't want you gobbler to hang up just out of range. I have had mixed results with dekes on fields, either birds running to them and my gun or having them demand their new friends come to them. If you use the jake, jealousy should help you pull them in even if they can see from a distance, if the bird your targeting is a dominate bird. I have seen jake decoys scare off other jakes, or at least prevent them form commiting all the way. It really depends on what your facing, and you should have a better idea on that after tonight.
If I understand you right, I would set up where you are thinking, with the decoys just outta sight. Calls should be enough to bring them around the corner, and the decoys should help them commit those last few steps and help distract the birds as you make final adjustments with your gun. Make sure you have your gun up and are ready to go as soon as you know they have hit the ground. It may be a very quick hunt. I have actually had a Longbeard fly from limb to limb and land right in my decoy setup right off the roost. Talk about a heart attack!
