Ii would create a task calendar to restrict the working hours to your "out of hours" time. Unfortunately there is not a direct method to restrict tasks from not being split over the different "out of hours" slots. The best thing I can suggest is to figure out what is the required path -- ie can one task be done one night and the other two happen another night? Then see if you can estimate how long each combination takes. If the series of 3 tasks take a total of 4 hours and your "out of hours" time ends at 11:00 pm -- then it must be started by 7:00 pm in order to finish by 11:00 pm.