Combining 2 switches into 1?

I have a 3-gang box, and I'm interested in combining 2 of the existing single-pole light switches in the box into 1 switch (that controls both lights simultaneously). My reason for doing this is because I want to install an in-wall timer (such as this:

http://www.intermatic.com/products/timers/consumer%20indoor%20timers/in-wall%20timers/st01c.aspx),

and I want the timer to control both lights simultaneously (same on and off times). I'd rather not have to purchase 2 timers, and the box itself does not have room for 2 bulky timers anyways.

My thoughts are to pigtail 2 wires from each switch together, and connect each combined pair to the timer, as in the attached diagram (wire colours are only used to identify wires in the diagram). The result would the 2 switches replaced by 1 timer and 1 blank in the box. Does this make sense, and are there any caveats or things I should watch out for?