TonyWilk:
If your program 'got lost' there's no guarantee that the software-controlled timer(s) would continue to work uninterrupted. Neither would timers guard against resetting the device or in a 'brown-out' condition.So, I say again:
I would suggest you AC couple the drive to the mosfets to give you some hardware 'insurance' against leaving one or both on all the time.
Yours,
TonyWilk
It should also be protected with a fuse.