It turned out to be fairly easy since the crashplan website has instructions on how to start and stop the service from the command line.
The start batch file is:
net start CrashPlanServiceThe stop batch file is:
start "" "C:\Program Files\CrashPlan\CrashPlanTray.exe"
net stop CrashPlanServiceI already followed the instructions here to automatically mount network drives, so I put the batch files in the same folder. Then I made two tasks in task scheduler, one to start at night and one to stop in the morning. I saw some people online had problems getting task scheduler to work with batch files, so I made sure the folder and batch files had administrators and system set to full control. I tested it and it seems to work great!
Oh, and to save energy, I'm using the software smartpower to automatically hibernate and wake up my computer. I set it to wake up 2 nights a week for the crashplan backup.