Have you investigated the "Desktop and Laptop Option (DLO)"?
NetBackup Desktop/Laptop Option (CL):
http://support.veritas.com/docs/286496
(there should be an Admin Guide for it too, somewhere)
Alternatively, you could run the backups on these during the day?
Yes, lots of people shy away from that option, but for a user machine is it really that bad?
Even better would be to use PureDisk (it's a little expensive if you don't have it already though).