What impact does a fall harvest that requires tracking of your fields as you combine cost?
You can look at costs of tillage to smooth out ruts and lost production due to compaction. We might assume an extra pass of disk/chiseling at $15/A (see http://www.extension.iastate.edu/agdm/crops/pdf/a3-10.pdf).
So if 25% of a field were rutted and production in those areas reduced by 10%; that would mean a 2.5% yield loss. At 200 bu/A and corn at $6/bu that would be $30 lost/A.
So perhaps $50 cost per acre for rutting is not unrealistic.