Don't do it!
Not sure if it's already been asked before but will you add some cheap alarm clocks for the red mission time displays? With a bit of luck stuff like that can be bought for less than five bucks per piece.
Seriously, having clocks on a set is a continuity nightmare. You have to remember to keep resetting them depending on the scene and take, and you always end up with continuity problems. If you have a chronometer on set, put it someplace you can only see it when you want to.