I would do this so it splits the work/drive sessions into 3 parts which are about the same between breaks
Start time \ 03:30
drive 3 hours \ 06:30
break 15 minutes \ 06:45
drive 1 hour \ 07:45
other work 2 hours \ 9:45
break 30 minutes \ 10:15
drive 2 hours 30 minutes \ 12:45
other work 45 minutes \ 13:30
3 hours
break 15
3 hours
break 30
3 hours 15 mins