Pretend you are a deer who uses the 80 acres. What would you do to avoid hunters? If there is a thicket or other area of heavy cover you can bet the deer will use it. Keep the probable wind and your approach path in mind when setting up your stand(s). Don't walk out across a large open area straight to your stand. Use the most concealed route. Have more than one location ready for different conditions (morning/evening, wind, etc.) and use the best one for any given outing. The main thing is to set up where your presence will not be obvious to the deer.
I wouldn't worry too much about disturbing the deer before the season opens. Farmland deer are used to human activity. If you go out and spend a whole day thrashing around in the woods, I'll wager my supper the deer will be back in less than 24 hours.
Deer will continue to visit soybean fields after harvest, but they often become more nocturnal. I would try to ambush them in an area of heavier sign away from the field edge. Even if they do approach the field, they will be on high alert, and any little mistake may cost you. They will feel more secure further into cover and are more likely to move around there during daylight hours.
