Start and end dates can be set relative to the check in and check out date by defining times greater than 24 or negative.
For example ACCESS_ENDTIME = 34:00 would create an end time of 10:00 one day after checkout (34 = 24 + 10 = 34hours)
ACCESS_STARTTIME = -10:00 would create a start time 10 hours before midnight of the check in day, i.e. 14:00 on the day before check in.