Cancel a job running too long?

We had this working fine under BE 2010, but now that we're on BE 2014, I think things have changed for the worse.

I have a backup job that I want to be available to run within a 24hr window. We *need* daily backups.  For this particular server, we need to lock some files to get a consistent state backup - but we can't keep the files locked for too long.  We have a pre-job to lock, and a post-job to unlock. No problem.

Here's the catch - I want the backup job to cancel if it runs longer than 4 hours from whenever it actually started. (not from when it was scheduled)

Under the job's schedule section, there's an option to cancel the job - but the minimum time is the reschedule time plus 1 hour.  I don't want that.  I want the job to run for sure today, but only for up to 4 hours from the actual start time.

Is there a way to do this with BE 2014?