I've just found this site, so this is my first msg. I have done my fair share of hours on a JD STS cutting all types of crops. If it was me setting up the combine for those conditions, without seeing or "feeling" the crop this is what I would start at.
1 small wire concave in the front, 2 large wire in the back.
Rotor at 900+. I have thrashed wheat with the bullet rotor at 1000 and haven't had issues with crack. The bullet dosen't thrash as hard the old type, which is a weakness in a lot of situations.
Concaves around 10, and probably opened a little farther.
Fan, 1000+. I like to run a lot of air, in those heavy conditions you will need it.
Top sieve at 16.
Bottom 6, if sample was fair.
A few years ago I really liked the STS series, however they are a hard combine to set up to do a good job all the time. A good buddy of mine went to the opposition and has not looked back.