5 Days To Starved Rock

Five days to the Starved Rock Marathon.  Did my last semi-long run today (12.5 miles).  The marathon is still intended as a good training run, so I won't be doing a major taper.  I will be cutting down on the mileage a bit in the next four days, but generally, I am training through the marathon.  My main goal is to run a solid race and come out of it healthy.  I want to be able to go out the next day and still have a decent run, maybe a little bit stiff and/or sore, but comfortable with a good four to six miles.  So what time goal can I expect and not have knocked myself out?  I feel I should be able to get in around four hours and basically have had a fairly easy time.  Although, deep down, I would like to be sub 3:55, which would be a Boston Qualifying time for my age.  This would be in case I might want to try to take the trip there next April.  No matter what I actually run, I am looking forward to Saturday and want to have fun.